Megumi Momono lives in Room #3 of Narutaki-Sou. She attended Washida University for one year before financial pressures forced her withdrawal, putting her studies on hold. Her appearance is marked by a distinctive ahoge hairstyle. Megumi frequently parties and drinks, often in fellow resident Shiratori Ryushi's room, disrupting his studies. She maintains a long-distance relationship with her middle school boyfriend, who studies cinema overseas. Deeply interested in films, particularly low-quality horror movies, Megumi possesses an extensive DVD collection in her room.

A complex past involving exceptional piano skills haunts her, associated with painful memories. Volume 9 of the manga reveals severe parental pressure during her youth to perfect her piano playing, culminating in a suicide attempt that left razor scars on her wrists. This trauma shapes her personality.

Megumi subtly influences relationships among Narutaki-Sou residents, notably encouraging developments between Shiratori Ryushi and Aoba Kozue. Her story concludes differently across media: the manga sees her accept her boyfriend's marriage proposal, leave Narutaki-Sou to join him abroad, and later appear in the epilogue with a daughter, Ruri, who admires Ryushi's children's books. The anime adaptation, however, keeps her at Narutaki-Sou, where she declines immediate relocation, asking her boyfriend to complete his studies and fulfill his dreams before reuniting.

She employs an ineffective repair technique called the "Russian Repair Method," involving forceful pounding to fix objects. Despite her outwardly carefree demeanor, her actions and relationships reflect an underlying resilience forged by past struggles.