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Married Woman Engaged in Fornication Sex "The pleasure of netorare I learned at a reunion... Don't make me cum in front of my husband..." 1

"You're harder than usual... bigger..."
Daiki joins a class reunion trip to a hot spring resort with his wife Mio. Riko, who once had feelings for him, also participated. Riko's husband, Ryo, jokes that Daiki is puzzled when he asks, "Would you like to try swapping?" He becomes overly conscious of Riko, and mistaking her for his wife, he crawls on her at night.
The two are unaware of their mistaken identity as husband and wife, and indulge in a thick sex session.
On the other hand, Ryo is also trying to set a trap for Mio... The cuckold adulterous exchange that develops between the two couples, and the four relationships become lewdly intertwined!

So its a mix of swinging and cheating/netorare