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A married woman who climaxes by peeping is peeped at... "You want to be penetrated too, right?" [18+]

"I...came...for the first time...while watching someone else's perverted sex...?"
While her husband is on a long business trip, Eira, who enjoys astronomical observation, happens to look into a room in an apartment building and witnesses a "sexual frenzy" taking place there. There, every night, various women are enjoying sex with a mysterious man, with ecstatic expressions on their faces....
As she peeks in on the perverted sex she has never imagined, her body becomes hot with desire and she begins to think, "If only I could be tormented like that...!" Eira's body becomes hot and her fingers naturally reach between her legs...
She becomes addicted to peeping masturbation, and then she sees an even more shocking revelation...