The mother deeply adores her biological son Makoto, always tenderly doting on him. Meanwhile, her stepson Tetsuo quietly harbors feelings of envy toward their affectionate bond. One day, Tetsuo accidentally witnesses Makoto and his mother engaged in a lewd act—and from then on, he repeatedly spies on them. Noticing Tetsuo's loneliness, the mother gently comforts him with her body.