Yusei Oya, a university student, desperately tries to protect and manage the dilapidated apartment building left by his deceased parents all by himself. The only tenant is the mysterious and beautiful lawyer, Ichijo. As he struggles with apartment management, kind-hearted Yusei is taken advantage of, and harassment from neighbors attacks him one after another. It was Ichijo, the tenant, who was repelling such wicked neighbors one after another with fierce methods. While gleefully inflicting cruel and extreme retribution, Ichijo shows unusual kindness and obsession towards Yusei. It seems she has a dark past connected to this apartment...?