His girlfriend really can read him like a book. Tetsu actually didn't know what's going on until toward the end of the title. Well, he better have a good gameplan the next time Yuki hints she thinks he's sleeping around on her bc if she suspects he has, logically it won't be hard to figure out who he's doing it with.
Sequel Idea: GF finds out about the affair, but instead of breaking up with the guy she invites the mistress over to their place to have a sex competition while the BF is drunk. GF's pride cannot handle that the mistress is sleeping with the BF since the mistress is her underclassman and the GF is a model. They proceed take turns having their way with the BF until he wakes up. They then proceed to have an intense threesome till the morning where both girls are wringing every single drop out of him to prove that they are superior. Morning comes and the BF is too exhausted to declare a winner \end. WHO SAYS NO TO THIS FOR A SEQUEL?!?!? CALL IT IN TO SANJUUROU AND WANI!!! (Jkjk)
 In all seriousness, i know this is too far - fetched to actually happen. But with all the WTF releases lately (at least in my opinion), my idea doesn't seem too far - fetched in comparison.
A realistic outcome would be Yuki finding out, her then bitch-slapping Hina, and then going and keying Tetsu's car after she dumps him. I don't think that would make a great sequel. The only option, I guess besides Split133's idea, is Hina and Tetsu continuing the affair without Yuki finding out.
Cuz it would be a fun change from the usual ntr or realistic routes that usually occur with sequels involving cheating. You're right that it's dumb, but dumb can be fun! Hentai doesn't need to be so serious or realistic all the time.
Hmm, so the cheating tag actually applies to the guy this time. "You got me all mixed up with Yuki-Senpai again"? Amazing how the addition of a single word at the end can change the meaning of a sentence so dramatically...So this isn't exactly the first time this has happened, and she seems perfectly content with not correcting his little misunderstanding? "Tetsu might just give you a hard time again"? I'm sure he will, but probably not the kind of 'hard' you were thinking of. What she did time and again wasn't exactly a good thing, especially since she's actually friends with her female Senpai...But somehow, I can't say I blame her too much for taking advantage of the situation everytime he gets drunk and confuses her for his girlfriend. Considering her comments about gazing into his eyes during sex and her reactions whenever she talks to said girlfriend, I'd say she genuinely likes him, but he was already taken.
Now that'a rare...