Adult PC Game: Ijikuri Mama 3 by Studio Kame Archive

Azusa's husband is away from home for a few weeks on business. With him gone she's sexually frustrated. While visiting her friend Haruno Tamami she and her son Kaede see her having sex with her son Hizashi. Running away in a hurry they go to her friend Aizawa Misaki and catch her having sex with her son Ayumu.

Not understanding the feelings he has by what he's seen Kaede asks his mother for help. She offers to teach him with her body.