beta
I'll be honest: age gaps are common themes of "nostalgic romance" -- it's a common theme in literature, and it's especially a common theme in BL, a genre centered in secrecy and acceptance and "forbidden" romance, or at least forbidden at the time.
For me, it's not a big deal as long as the younger party wasn't exploited, and there's genuine interest and affection coming from them without coercion or brainwashing coming from the older party.
The start of their romance and first time of their sex was consensual in my eyes, regardless whether Mori was morally correct or not (he wasn't). Their second sex in their adulthood was tense, and it was bordering dubcon, but Tora was sober and has the strength to fight him for real, as seen in him hitting Tetsuya in the hallway before the sex scene. Tetsuya was saying Tora has to fight him for real and not hold back in punching him if he really didn't want to accept Tetsuya.
Questionable and it's probably coercion or smth of the like, but this kind rough yes or no communication is so freaking common in mangas made in the 2010s especially when they involve macho men. Tora and Tetsuya are former gangsters, plus Tora's a tsundere, so rough communication is not unexpected? What's important is the aftermath.
The aftermath of their 2nd sex showed them to be at peace and Tora didn't show signs of unhappiness or trauma.
After that, Tetsuya didn't force himself on Tora.