Ayumu, a lonely latchkey kid, enters into a "sugar sister" arrangement seeking companionship and home-cooked meals. While his new companion initially appears to be a kind and nurturing elder sister figure, the relationship quickly shifts into a sexual arrangement based on "favors." As Ayumu falls into this cycle of pleasure and dependency, he becomes entangled in a seductive lifestyle that threatens to disrupt his daily life.
After being ditched by his date at a hot spring resort, college student Doi Takanori unexpectedly reunites with Tokiko Kurahashi, a clumsy former classmate attempting to redo a missed school trip. With no other accommodations available, Tokiko shares Doi's room, where their nostalgic reunion sparks an intense physical and emotional connection in the private open-air bath.