Bokura wa Minna Kawai-sou
The Kawai Complex Guide to Manors and Hostel
僕らはみんな河合荘
Usa, a high-school student aspiring to begin a bachelor lifestyle, moves into a new apartment only to discover that he not only shares a room with a perverted roommate that has an obsession for underaged girls, but also that another girl, Ritsu, a love-at-first-sight, is living in the same building as well!
(Source: Kirei Cake)