University student Rio is currently dating the handsome owner of a reputable Japanese-style confectionary store. As a gentleman, he doesn't pressure her into sex, and even when she stays the night, nothing happens in bed. Gazing at him while he sleeps, Rio remembers something her friend said.

"Like, y'know, guys have such big fingers, so like, even fingering feels so amazingly good, right?"

She then takes his hand and begins using it to satisfy herself, but then her boyfriend asks, "What are you doing with my hand?"

While she is still befuddled by the abrupt question, he begins fondling and giving pleasure to her...
and slowly, but surely, Rio's inexperienced and virginal body is dyed by his hue.

There is a TL and R18 version.