Pastel by Toshihiko Kobayashi. An Ecchi manga rated Older Teen, published in English by Del Rey.

High schooler Mugi meets Yuu under embarrassing circumstances at a seaside inn, and before long Yuu and her younger sister Tsukasa are living in his house. With his once-quiet home turned into a lively, chaotic household, Mugi tries to keep his growing feelings for Yuu in check while dealing with awkward misunderstandings and attention from other girls. A breezy, fan-service-heavy romantic comedy.