Adult PC Game: Sleep Learning v3.0 by Armanium Archive

Overview:
Story.
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.​

Sleep Learning v3.0 by Armanium Gameplay Preview