Summary from Manga Abyss :
My name is Kohinata An. My parents went overseas to work and left me to live with my grandma. However, she was hospitalized all of a sudden, leaving me as the manager of her lodging house! Furthermore, there are three cool guys lodging there! Ba-dump. Ba-dump. But one of these three guys, Ryuu-kun, seems to hate me for some reason... What for--?!