The Rogue in Room 3

Yuya Hanamaki is a university graduate who has to take over managing his grandpa's apartment building after a back injury. Reluctantly, Yuya begins his duties. And the first thing he must do is greet all of the tenants. When Yuya gets to room 3, he lets himself in, as advised by one of the other tenants, and out comes a familiar face from the piles of mess... Yuya has fond memories of growing up in the apartment building and meeting very nice people. But this Ikezawa is nothing like he remembers!

(Source: Futekiya)

Note: Includes three extra chapters.