Feels like the author is just arguing with themselves at this point
They did something similar in Mii-chan wa Kawaretai too. But at least in THAT series, the MC was kind of justified in being wishy-washy, given the god awful "cat girls who want to stay human gotta commit by having sex before they turn 18 btw" set up. Even the author seemed to realize how creepy and not-at-all romantic having that arbitrary magical deadline was, so they kind of soft-retconned aspects of it and made other characters more sympathetic to the adult MC being hesitant to committing to banging a minor...
But in THIS series, there isn't really any external pressure other than the looming college entrance exams, which are a full year away, and it really just makes Asahi look lame and kind of pathetic. Like the dude is honestly pretty boring and doesn't even really have any other hobbies other than KPop, so it's not like he has a ton of other stuff taking up his time and making it hard to prioritize study time.
Not only that, he even has a super smart older sister who literally works at cram schools and specializes in teaching her students how to study efficiently. But despite that, he's rejecting her advice and trying to ban himself from seeing his mutual love interest or even engage in his one and only KPop hobby for a full year to focus on studying, which would obviously just lead to stress and burnout.
It's just such a stupid and unproductive idea, even for a high schooler, that it really lowers any likability he had. He has everything going for him and has a clear path to his happiness, but insists on running into brick walls of his own making. Sawai and Tsukiko are honestly too soft on Asahi for how obnoxious he's being.
