After her husband is transferred overseas, Rino lives alone with her stepson, Yoshio. Lately, she finds herself becoming aware of him as a man, causing her inner turmoil. Meanwhile, Yoshio, though drawn to the temptations offered by his friends, secretly harbors feelings for Rino while gradually succumbing to a life of pleasure. Eventually, those suppressed emotions begin to surface, and one late night, Yoshio confesses his deepest desires. As the truth comes to light, their forbidden feelings take on a new, passionate form.