A black man moved in next to Mizuki Hayakawa, and she quickly became friends with him and invited him to her house to teach her English. But that was just an excuse as Mizuki discovered that black guys always have a big penis, and she was curious about how it would feel to have sex with it.
Taking that opportunity, she secretly cheated on her husband to have sex with the black neighbor, and one day her husband discovered that she no longer felt pain during intercourse with him, though he was puzzled, he didn't understand why that was the case...