Ibara no Naka no Hana

Asagi Sakuraba has had to single-handedly raise his younger sister, Aoi, ever since their parents abandoned them. Aoi has severe asthma that requires her to go in and out of the hospital, so Asagi began working at an early age to support them both. His goal is to make life as easy as possible for his sister. Therefore, when the two are suddenly forced to leave their home in the middle of the night, Asagi must swallow his pride and ask for assistance from a wealthy heir he met only recently—Kaname Hiiragi. Kaname takes Aoi to the hospital and brings Asagi to his own home, a luxury penthouse high above the rest of the city with restricted entry and exit. Although initially impressed, Asagi wonders if Kaname is as lonely as his surroundings appear. That must be the reason why Kaname proposes a contract to pay Aoi's medical bills and tuition in exchange for Asagi living with him; yet it does not explain the demand that Asagi cannot talk or meet with anyone, nor leave the premises, without Kaname's permission.