On that day, I did hear it. "The tidal wave that changed my destiny..." Tamao Kashiwagi (27 years old) is a so-called "mourning woman." She lost her parents when she was a child, and ever since her relatives spoke ill of her, she has had a hard time speaking. One day, Tamao meets a boy named Umi, who is in the same situation as her. Tamao sees her old self in Umi-kun and decides to take him in. However, there are many difficulties living together with a mourning woman and a dark-natured boy...?