After finishing his solo work assignment, Yuuzou returned to Tokyo but could not secure housing at the company dormitory, so he moved in with his older brother and his brother's wife. Having been too busy to attend his brother's wedding, this was his first time meeting his sister-in-law, Hikari. As Yuuzou sees Hikari for the first time, his heart gradually becomes captivated by her, setting in motion a story of forbidden desire and emerging emotions.