"I never thought that I, who was an ordinary housewife, would have such a relationship with my younger brother at a good age ..." Aya Kurahashi (Ai Kano), an older sister in her late 30s who has two children, has decided to take on the housekeeping agency of her younger brother, Takumi, a single aristocrat in her 30s, to supplement the family budget. However, before she knew it, Takumi, who had awakened to a mature woman fetish, had a secret lust for Aya. Takumi, who got drunk and broke up the relationship, continued to seek her after that and proposed a split relationship. - While saying "for the family budget", Aya's body drowns in the pleasure of the affair that she tastes for the first time.