Taming the tiger
How many chapters do you consider "long" XD That's a tough one to fulfill... how about the Sabita/Hadakeru series. Someone made a guide cuz it's told across several manga:
0. Aazami - past Yumi x Kan
1. Sabita Yoru Demo Koi Wa Sasayaku -Yumi meets Mayama and breaks up with Kan chan
2. Renai-rubi no Tadashii Furikata (ch3.1 - 3.5) - Kan meets Shuuna and turns uke
- Narrow (Place collection) - dj Kan x Shuuna smutty sidestory
3. Hadakeru Kaibutsu - continuation Kan x Shuuna (Shuuna's POV as far, timeline parallel to no.2 for ch1)
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Personal opinion - best reading order 1, 0, 2, 3
https://www.mangago.zone/read-manga/the_man_at_night/ (100 chapters. They’re strippers!)
https://www.mangago.zone/read-manga/sura_s_lover/ (92 chapters + side stories. Bit more of a dark/twisted story)
https://www.mangago.zone/read-manga/profundis/ (96 chapters)
https://www.mangago.zone/read-manga/cold_blooded_beast/ (85 chapters + side stories)
https://www.mangago.zone/read-manga/my_hyung_s_lover/ (64 chapters. Also more dark/twisted)
https://www.mangago.zone/read-manga/butler_nabit/ (65 chapters)
https://www.mangago.zone/read-manga/love_shuttle/ (84 chapters + side stories)
https://www.mangago.zone/read-manga/my_suha/ (116 chapters + side stories)
Also agree, not sure what you consider “long”, but I have more in this list where all are at minimum 50 chapters long. 99% of them have smut. https://www.mangago.zone/home/mangalist/3223395/
Guys I’m bored, give me something good with smut and a lot of chapters