Naimono Nedari no Koi-tachi wa

Hami, who dreamed too much of love, suddenly found herself a sophomore in college. Thanks to her half-brother, Riku, who enrolled at the same university, she ended up going on a date with Mizuki-senpai, a boy she has a crush on. But behind the scenes, Riku, who is obsessed with Hami, has his own motives...

(Source: Shogakukan, translated)