ROE-475 | My wife, whom I thought was a tuna for 16 years... was having an adulterous sexual encounter that caused her to convulse and reach a fish-like orgasm, continuing until she fainted. - Momoko Isshiki

Momoko, a beautiful and kind married woman, lived happily with her accomplished husband, Sadaharu, and their nephew, Hayato, who was a ronin (a student studying for university entrance exams).

However...this couple had one big problem.

That was...Sadaharu was terrible at sex, and Momoko was extremely unresponsive.

One day, Hayato witnessed this and was deeply shocked by Momoko's unresponsiveness.
Although he was a virgin, Hayato was confident in his large penis and the techniques he had honed at the brothel, and he thought he could satisfy Momoko. He kissed her and began to have sex, but...her orgasm was beyond his imagination...