Gohoubi wa Yoru ni Choudai

Hinano, a member of the library committee, finds Haruna, who is famous for being super popular, sleeping in the library. Hinano is entangled with Haruna and, even more so, is robbed of her first kiss...! She goes home thinking about pretending it never happened, but for some reason Haruna is there. Then her mother suddenly tells her that he's going to live with them for six months!

(Source: Starts Shuppan, translated)