From MangaHelpers:
44 year old Tsutsumi Kyosuke is happily married to his wife Naoko and, between the two of them, they have a son, Takuya, that they are proud of. Although he was surprised when Takuya said that he was getting engaged after graduating college, Kyosuke was happy for him. But that all changed when he met Himiko, the fiancé, because she was Kyosuke’s ex-girlfriend from 22 years ago. Himiko’s beauty had not deteriorated over the years and could make even a young man like Takuya head over heels for her. But Kyosuke knows that Himiko has reappeared back into his life for revenge because he left her when he realized how crazy and mentally unstable she can be. Himiko starts manipulating people around Kyosuke and makes his life unbearable, but this time, he has nowhere to run.