Playing with my Brother's Wife

The main character is shocked to meet Miki, his older brother's fiancee, because she is the woman he used to love. He didn't even know her name, but she appears in front of him again.... They get married after a while, but his older brother goes abroad on business. Like this, he starts living with his parents and Miki. One night, he accidentally sees Miki masturbating. He loses his self-control and pushes her down on the bed.... Miki tries to resist it at first, but she gradually gets sexually excited and they finally sleep together.... They promise to keep it secret, but their relationship doen't end. Miki knows it's not a right thing, but her body can't resist it....