After losing her husband, Mio is a mother who has been working part-time to make ends meet and raise her only son. She struggles to make ends meet and is unable to pay her rent, but a man in the neighborhood helps her out. However, this leads to Mio being asked to look after the man's son, Katsu. Katsu, who doesn't know his mother, becomes curious about Mio's body and approaches her at every opportunity. He treats her like his own son, touching her body, taking baths with her and having her take care of his erect penis, and even taking advantage of Mio's sexual frustration and having sex with her... Mio begins to feel pleasure from sex with Katsu, and they end up building a relationship where they desire each other on a daily basis...