Momoka's older brother is the classic "loser guy"—jobless, broke, unable to keep a steady job, living off others, yet constantly cheating on women. Despite his flaws, Momoka deeply cares for him. She's kind-hearted, can't say no when asked for help, and easily gives in to pressure. Throughout her life, that gentle nature has backfired—instead of just covering for her brother's messes, she's ended up cleaning up his sexual escapades, especially using her large breasts. Yet she can't bring herself to abandon him. For the brother she loves so much, she's ready to do absolutely anything.