Makoto Ashirai is a young woman who resides in Tsubaki manor, the same apartment building where Haruma Kawagoe, his sister Choco, and the tenant Yasuoka live. She is physically characterized by her medium-length orange hair and yellow eyes, and she is almost always seen with a can of beer in her hand. Her appearance and behavior often lean toward the provocative; she frequently teases Haruma by wearing revealing clothing and insinuating that he is secretly interested in her body.

Her personality is a mix of outwardly indulgent vices and underlying decency. She is a heavy drinker, lazy, and prone to mooching food from her neighbors. Her sense of humor is decidedly adult and she is a shameless flirt, with a tendency to make sexually suggestive comments. She also displays a scheming and somewhat manipulative side, though her schemes are usually harmless or intended for amusement. Despite these flaws, she has a good heart. When the original landlady of the building fell down a staircase and injured herself, Makoto was the one who came to her aid, revealing a responsible and caring side. She also has an odd, persistent interest in the bust size of the current landlady, Chitose Serikawa, which makes Chitose uncomfortable.

Makoto works as a model, but she keeps this profession a secret from the other residents. She does not flaunt her career or seek recognition for it, adding a layer of privacy to her otherwise open, uninhibited lifestyle. In the story, she serves as a supporting character and a source of comic relief, often lounging in hallways or barging into Haruma’s apartment to drink, eat, or tease him. Despite her apparent laziness and constant state of inebriation, she can be remarkably perceptive and insightful in social situations. She proves herself a steadfast friend when the occasion demands it, though her reliability is limited by how quickly she passes out from drinking.

Her motivations are not deeply explored; she lives for the moment, seeking pleasure in alcohol, food, and playful interaction with her neighbors. She has no major character arc, but her inherent kindness and willingness to help others indicate a genuine, if easygoing, moral compass. Her key relationships are with Haruma, whom she constantly teases; with Choco, the innocent little sister, whom she treats with relative normalcy; and with Chitose, whose reactions Makoto seems to enjoy provoking. Ultimately, Makoto Ashirai is a colorful neighbor whose external vices mask a fundamentally good-natured person who can be counted on in times of need.