Well, A high schooler in Japan would be from 16 to 18 years old. College student from 18 to around twenty something. I don't think it was meant to be such a big age gap, he probably was around 19 and expected someone around 17.
Oh, I wasn't worried about the age gap. It was more of a... CRIME I WAS WORRIED ABOUT! LOL. Being a high schooler is still being a minor, even more so as he was actually a middle schooler pretending to be older. It didn't hurt them, thankfully. Yes, high school students, although still minors, may be sexually active but just... remember that it is still criminally (and ethically) wrong to have sexual relations with a minor. Laws in Japan differ than in my country but... hopefully you get what I'm trying to say.
Lol, it's not a big deal. I didn't care too much. It's not the craziest thing I've read in a manga. I just needed to add the fact that they had sexual activities despite one of them being a minor because... the comment trolls might come after me XD
Can we get a story for Takumi-san?! Like, please?! He seems like a sweet guy who tries to comfort even his sex-friends. Yes, he shouldn't have sex with a high schooler (who was actually a middle schooler at the time), but he seems like a good person!