. - It is summer vacation, but the protagonist is not taken anywhere. - Then he receives a phone call from his aunt saying, "Won't you come to visit me? and he gladly accepts the invitation. - The protagonist is happy to accept the invitation, and goes to her house right away... - Nighttime Mischief - At night, when everyone has gone to sleep, the protagonist can sneak into his aunt's bedroom. - Repeatedly pranking her will raise her "sexual maturity level" and increase the range of her pranks. - Number of CGs - 15 basic pictures + differences, standing pictures, etc.