
Ahahah. I was actually looking for commentaries on Jake's confession about him claiming their relationship would be better after the mission was over. But I didn’t go page by page. I just look at the posting date of the chapter then, on the comments, page selector I go chunk by chunk until I find the date I am looking for.
Anyway.
Not gonna lie that I knew the answer to your question. So if you insist here are the chapters you are looking for:
Chap 2 (end) and 3: A deal on the parking ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-208474/pg-1) – Content: Blowjob by Shin on Jake with ass groping. Bonus: Offer of inserting finger in Jake, the latter being flattered by the offer and encourage Shin to try if he feels like it.
Chap 9 (end) to 11: Back alley favor ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-208477/pg-1/) – Content: Blowjob by Jake then tight job done on Shin, with promises of full sex the next time they met.
Chap 16: Rescuing Shin ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-208480/pg-1/) – Content: Hand job on shin who has been drugged up. Bonus: First initiative of Shin licking Jake hear to see his reaction.
Chap 17 to 19: A clean bed ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-208481/pg-1/) – Content: First time Jake and Shin have intercourse. Bonus: Jake gives his full name. First ear biting by Shin. First arm pit liking by Jake. Implication that Shin used to be a top. Mention that Jake liked being ride and possible foreshadowing of him liking being dominated.
Chap 26 to 28: Cop play at the casino ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-208484/pg-1/) – Content: Jake in cop uniform bring Shin in a Casino hotel room to remind him to only sleep with him and have sex with him in his uniform to make his point. Bonus: Implication that Shin like to see Jake in uniform and that Jake is jealous. Kiss mark rebranding. And second time Jake ask to have his tongue sucked.
Chap 37 to 39: Late night visit at the garage. ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-83407/pg-1/) – Content: Deep throat by Jake then intercourse on top of a car hood. Some armpit fondling. Bonus: Shin mentions he finds Jake sexy, especially his chest (with the holster) and want to suck on it. He also mentions he surprisingly enjoys sex while knowing a camera is recording them from one of Jake’s car.
Chap 48 to 50: Bargain for Gren under the shower. ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-210348/pg-1/) – Content: Foreplay under the shower then full on intercourse that ends with them hugging crouching on the floor under the running water. Bonus: Rim job by Jake.
Chap 54 (end) to 59: A Rainy night ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-150835/pg-1) – Content: Full sex scene with foreplay (rim job, blow job, fingering, armpit and ear licking, cop cosplay and intercourse) Bonus: First chest fondling by Shin. Jake mentions he like his name being called during sex and first mention of him wanting a bed headboard. First time Shin will wake up with Jake by his side. Mention that Jake likes to hug Shin in his sleep but is annoyed at his habit to sleep on his stomach (solution to that problem on chapter 91). First mention of a “us” between them.
Chap 63 to 65: Car ride ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-210355/pg-1) – Content: After Shin confesses in the car to Jake he will protect him if he ever need to run away and goes with him wherever, Jake bring them back to the garage to have sex (fingering, hand job and car play for Shin, plus riding position, armpit licking/biting and kiss/tongue sucking begging for Jake). Bonus: mention of Jake pre-cum being like a water fountain. Possible foreshadowing for future squirting by Jake. Mention again of Shin wanting to top Jake, but Jake deny saying it isn’t his cup of tea.
Chap 68 (end) to 69: The break up ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-231928/pg-1) – Content: Blow job by Jake similar to their first encounter by with the position reversed.
Chap 83 (end): From a distance ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-246992/pg-1) – Content: Jake is spying on Shin after finding him back and listen to him masturbate in his motel room.
Chap 89 to 91: Reunion ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-254679/pg-1) – Content: After the funeral, Jake and Shin return to their motel and dive in an aggressive a passion make up sex (power play, chest and ass fondling, armpit job, cop play, armpit and ear liking/biting and full intercourse). Bonus: Jake got his headboard, but Shin refuse to call his name at his request.
Chap 103 to 105: Cops Debriefing ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-291716/pg-1) – Content: Coming back from their bugging job, dressed as cop, Jake and Shin clear things up in the garage in another pretty intense sex session (power play dom/sub, kneeling blow job by Jake, intense intercourse with cosplay kink) Bonus: Squirting and dry orgasm for Shin, request to squirt to by Jake (with implication he might need to bottom one day), Shin threatening to shove thing in Jake again, another mention that Jake pre-cum is pretty intense, both admit being into to cop uniform and calling each other sexy. Confession of Jake that he want a relation after the mission is over, and massive hug after sex. Switching foreshadowing more and more implied.
Not smut but sexy/relationship topic:
Chap 6: First Kiss ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-34710/pg-1)
Chap 21: Hotdog Lunch ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-56509/pg-1) – Content: Discussion around a hot dog about their first time together, Jake experience and expectation. Bonus: Revelation that Jake bottomed before and didn’t like it, but once he has manage to make Shin cry in bed, he may accept to do it again if he feels like it then.
Chap 69 to 70: Domestic life ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-175015/pg-1) – Content: Some important discussion about lube, their position in sex (another mention of Shin wanting to top Jake) and their life together. Then an intimate post sex moment.
Chap 96: Shooting range ( https://www.mangago.zone/read-manga/shutline/uu/br_chapter-276527/pg-1) – Content: Some sexy fooling around while Jake teach Shin how to shoot a gun. Bonus: some mention again of Shin liking of Jake in cop uniform.
And for the animated series: Episode 1 (end), 2, 3(end) 4, 5(end), 6, 8, 10 (end) and 11.
https://kisskh.co/Drama/Shutline/Episode-1?id=9316&ep=158611&page=0&pageSize=100
Enjoy. And message me if you have the need to spot the smexy chapter in another series. (≧∀≦)

You know what...? I just realized I confused two conversations I was on and sent here the list I was supposed give someone that wanted a listing of all the smexy scenes of the story... while you guys were only looking for the chapter mentioning Jake prior experience. ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ It is in my list but it is a long list. So I will give the short answer:
Jake mentioned bottoming in chapter 21.

Sorry about the wait. I was travelling and couldn't do the listing. Here his the breakdown for "Under the Green light"
Chap 3: First Encounter ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-79907/pg-1) – Content: Mutual hand job in a toilet booth Bonus: First kiss and facial
Chap 6 (end) and 7: Be my model ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-14145/pg-1) – Content: Touching, caressing, blowjob by Matthew and foot job by Jin. Bonus: Blindfold game. Jin asks Matthew to practice blowjob because it was bad.
Chap 8(middle): Immersion ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-17241/pg-1) – Content: Short masturbation.
Chap 12: Unsatisfied ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-38645/pg-1) – Content: Occasional Jin’s bar hook up, under influence. Intercourse with blowjob. Bonus: Jin is shown to be the top, but mentioned he needs something more, implying he is craving to the bottom again, just like he is craving drug. But just haven’t found the right partner. Also think of Matthew, requesting the blowjob to be done more awkwardly, closer to how Matthew did it, implying Jin is being more responsive to it. Jin’s addiction to drug and pleasure is fully shown here and seems to be switching toward Matthew as replacement.
Chap 13 to 16: I Need More ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-38646/pg-1) – Content: After failing to be satisfied at the hotel with his hook up, Jin, still high on drug, reunites with Matthew in hope to get the satisfaction he is looking for and to put an end to his splitting headache. The both engage in a passionate sex session, including kissing, fondling, blowjob by Matthew, hand job by Jin, self-fingering and full intercourse (multiple climax). Bonus: Hang tied game, Matthew’s first time going all the way, Jin joking about Matthew practicing blowjob as he is doing a better job now, revelation that Matthew trained on a dildo. Jin bottoming again for the first time in a long time and his pride getting the better of him when he realize that Matthew has more stamina than him, who is normally an addict to sex and can’t get enough. Also Jin teaches Matthew how to give him pleasure during penetration which his student immediately put in practice.
Chap 19 to 23: Venting Out ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-27444/pg-1) – Content: Both frustrated, Jin by his earlier encounter with his former nemesis, and Matthew by Jin’s provocation after he kissed his previous hook up in front of him, the duo goes into a car to have sex, going from hand job, to blowjob, then a rim job down on Jin to fingering and frotting before going full on penetration. Bonus: Facial, cum licking and car sex. Joke about Matthew learning new things on its own but also from what Jin teaches him, even if the latter doesn’t realize it. First time with Matthew while Jin’s isn’t under influence, which helped with pain the last and first time they did it. However Jin’s pain goes away and he enjoys it for the first time sober.
Chap 31 to 33: Only Me ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-69333/pg-1) – Content: After date night at a hotel, Jin and Matthew share a pretty intense intimate moment, where Matthew let his obsession take over a bit too much. This starts with foreplay in the hall entrance, to fooling around in the shower before going wild on the bed. Bonus: Jin suggest Matthew should bottom and Matthew says he wouldn’t mind if it satisfies Jin. Although the latter says they have all the time to teach him how to switch. Also Matthew cum in Jin, as if to “brand himself in him”. Matthew is showing he is jealous. And Jin rejects his feeling saying it is in his head.
Chap 46 to 51: You are just a dream ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-189709/pg-1) – Content: After Matthew got roofied at a party and, thinking he is dreaming, forced himself on Jin who was nursing him. Even if Jin goes with it, because he knows from experience what the drug is doing to Matthew, the sex is pretty rough and violent, and ends up with Jin’ stiches being reopen. Warning! This part contain violent behavior under the influence, leading to derogatory comments, strangulation, forced fellatio and brutal intercourse.
Chap 55 to 56: The bath ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-207734/pg-1) – Content: Matthew helps Jin take a bath with his wound, and while checking his hole to see the damage he had done, aroused Jin who wants more. Obeying the doctor’s order to refrain from sexual intercourse, Matthew resolve to fingering his lover.
Chap 63 to 65: Hold him back ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-221844/pg-1) – Content: Jin has been brought to Matthew severely drugged after he go ambushed. Completely high, Jin ask Matthew is help to release him from his aphrodisiac fever. Starting from masturbation then fellatio, fingering, rim job it will end in full intercourse during several days, where Jin will come in and out of consciousness, and even hallucinate about what his former boss did to him. Bonus: Jin will tell Matthew he only need him. Warning: Nonconsensual drug injection.
Chap 76: The Itch ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-244746/pg-1) – As they are still in the museum, Jin and Matthew starts kissing and get hot and heavy. Almost being caught by the night guard, they relocate to Matthews place, where Jin mentions that his scars itch, and so does his inside, to which Matthew offers right away to “scratch that itch”. Follow a very passionate love making session, which contain very deep penetration, reverse cowgirl-ing, missionary and side penetration. Bonus: Jin wearing a thong, squirts and Matthew reach climax by hearing Jin telling him he likes him too. After sex, some hickeys can be seen on Matthew’s lower back, implying that Jin may have, at the very least, do a rim job on him or play with his ass, hinting back at his suggestion (in chapter 31) of training him to bottom.
Chap 77 (End) to 78: The birthday ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-245645/pg-1) – Content: Jin talks about his sex life with Matthew while this one is studying abroad, which is pretty intense when he is home but too much far apart. Eventually, Jin is becoming pent up from the waiting and starts masturbating with the dildo Matthew bought at the beginning of their relationship to improve his blowjob skills. Matthew ends up calling as Jin is enjoying himself, which turns into a short session of phone sex. Luckily Matthew was just behind the door, wanting to surprise Jin with a gift, and jumps into the action right away. After some dildo foreplay, the two men share a pretty intense coitus, in about “all the position there is”. Bonus: Jin masturbate sniffing Matthew’s flannels. Jin cums just from his assplay then just from Matthew entering him.
Relationship moment:
Chap 17: I’ll be waiting ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-43006/pg-1) – Content: Jin suddenly French kiss passionately then tenderly Matthew hinting to a little affection, although he leaves the studio not promising to come back.
Chap 26 to 27: It wasn’t me ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-59891/pg-1) – Content: Jin visit Matthew’s studio and find him napping, surrounded by all the drawing he made of him. Clearly surprised by the amount of dedication Matthew has on him, Jin ponders about why he chose him to be his model. Why specifically him? As he decides to leave, Matthew caught his jacket while still asleep and blurred a plea of innocence. This leads to the reader entering Matthew’s nightmare and see his past in the orphanage he grew up in after his parents death and where he actually met Jin for the first time. We also learn what sculpting means for him: To preserve what he can’t possess.
Chap 28: I created a monster ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-65061/pg-1) – Content: Jin brings Matthew on a sort of date where he buy him cloth and brings him to a fancy restaurant. There Matthew said that despite the sex between them being just a deal in exchange for the modeling favor, he needs a better definition of their relationship, then admits that he hates the idea of Jin sleeping with other people than him. Therefore he accepts to be whatever Jin wants him to be, if it means keeping Jin close. Bonus: A hint of a more serious relationship is pointing its nose, but Jin is still trying to make their bond casual and just pure sex. Obviously, Matthew is more obsesses, while Jin is resisting to any emotion temptation. In short, they are starting to have differences within their relationship.
Chap 34: Something unchanging ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-75294/pg-1) – Content: Matthew reflects on Jin’s rejection of his feeling and while looking at him sleeps, confirm that it is not in his head, even if Jin can’t remember him, Matthew shaped his life because of the impact Jin had on him has a child. Reason why he wants a statue of him, because he wants something that is not changed by time.
Chap 42: This is not your place ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-187318/pg-1) – Content: After realizing Matthew is the kid from his past he wanted to build a house for, and lost himself in the way to a “better life for them”, Jin tries to push him away out of fear of what could happened to Matthew if he remains by his side, but Matthew resists and offers to be used “like a dildo”, which horrified Jin, as he realized how far Matthew is willing to do just to stay by his side.
Chap 52 to 53: Stay by my side ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-201083/pg-1) – Content: After getting himself re-stitched up from being forced upon by a drugged up Matthew, Jin confronts Matthew about their past and his weak apologies. Even if Matthew understand he raped Jin and feels remorseful, Jin tells him sorry and fleeing won’t cut it. Therefore, he orders him to stay by his side from now on. Bonus: Kiss.
Chap 56 to 57: Ordinary Life ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-210994/pg-1) – Content: some example of Jin and Matthew domestic life, as Matthew lives at Jin’s place. From cooking his breakfast, to washing him, to nursing him and eventually going on a movie date together. Bonus: Jin sleeps correctly and called Matthew his boyfriend.
Chap 74: I’ll go to you ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-241738/pg-1) – Content: Revelation that Jin has led his life all this time to keep the promise to give a home to Matthew. Just like Matthew life was shaped and influenced by Jin, Jin’s life was molded with Matthew in mind. After Brandon is arrested, Jin and Matthew reconcile and Jin kiss his lover telling him he will come to him this time.
Chap 75: The thing that won’t change ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-242847/pg-1) – Content: Matthew waits for Jin to come see his first exhibition and as the last day arrives Jin hasn’t show up. Matthew reflects that it doesn’t matter since he has Jin’s statue, he no longer need to wait for the man. But has he kisses the statue, he realize that the real Jin is still what he wants. At that moment, Jin arrive with a bouquet and Matthew kisses him, crying tears of joy, as his wait has finally bear his fruits. He then shows his statue to Jin, who is surprise that his vision of him is a person reaching out. Matthew explain that he knows Jin isn’t prefect, but he is perfect for him, and he knows Jin is an ever changing person, but this time, despite change being what Matthew fear the most, he want to witness it all with his own eyes, what his lover will become. Because what will never change is his love for Jin. To which Jin ask to continue being Matthews’s model for the rest of their life. Bonus: Jin blushes like a schoolgirl and Matthew confesses.
Chap 78 (end): Finale ( https://www.mangago.zone/read-manga/under_the_green_light/uu/br_chapter-246886/pg-1) – Content: Matthew gives an ankle bracelet to Jin and they chose that day to be Jin’s birthday. Then years passes, Matthew his having his solo exhibition, and during an interview, he explains that Jin is his model, his lover and his family. On his end, Jin has finally build his house to share with Matthew and propose to him that they lives together for the rest of their life. Bonus: Matthew is color blind and can only see shades of green, reason why the comics (and his solo exhibition) is called under the green light, because that is how he see the world. Jin proposes and Matthew says yes.
Correct me if I’m wrong it’s been awhile since I’ve read the start of this but didn’t Jake say he’s tried bottoming once and didn’t like it, that or I’m tripping