During the summer break marked by record-breaking heat, Ryosuke reported to his aunt Kotoha, 'I got my first girlfriend.' However, Kotoha, who had been gasping in loneliness since her husband's death, lost her reason at his innocence. She stealthily evades her family's gaze and gently tempts him, saying 'Practice for SEX,' but the pretense of guidance gradually falls away, transforming into frenzied lust. On the final day, Kotoha restrains Ryosuke's limbs and indulges in managing his ejaculations to their limits. Seven days of debauchery, Ryosuke had no way to resist his aunt's venomous fangs...
