Since childhood, Mako has harbored a fascination with her anus. One day, after being brought along by her mother to visit a relative, she meets her uncle and begins opening up about her sexual desires. The uncle then introduces her to outdoor blowjobs, drinking urine, and the intense pleasure of having her anus penetrated with his tongue. However, Mako soon discovers that this uncle is more than just a family relative—he's a pervert having an affair with her own mother. Driven by a desire to surpass her mother, Mako resolves to surrender her anal virginity and offer her golden nectar to her uncle. By finally accepting her own feces, she crosses a new boundary into uncharted territory.