After being dumped by his girlfriend and left heartbroken, Atsushi turns to his kind and gentle aunt, Ayu, for comfort—the woman he's secretly admired for some time. Being close in age and having always treated him like a younger brother, Ayu deeply cares for Atsushi and tries her best to console him. But suddenly, Atsushi pulls her into an embrace and kisses her passionately. Though initially shocked and confused, Ayu gradually begins to respond as her emotions rise. Their relationship has now crossed a line from which there is no return.