Osananajimi wo Shuuchaku Otoko ni Sodatete Shimaimashita

A young woman, the sole daughter of a major business family, became mute after her mother's death and has only communicated with her childhood friend, a boy whose growth was halted by a curse. They lived together for 15 years as a family. Believing a superstition about finding happiness through a pre-20th birthday kiss, she kisses him, causing him to suddenly age into an adult. This change intensifies his existing feelings for her. The story follows the evolving relationship between a woman who has never experienced love and a man who becomes increasingly devoted to her.