Sobo to Boku: Obaa-chan, Nanika Dechau yoo The Motion Anime

Description:

Centered around wife and grandmother Minako and her affair with her grandson, Shouta. It started when Minako was woken up by the feeling of her breasts being squeezed. She opened her eyes only to see Shouta, who had been sleeping next to her. When Minako asks him if there was something wrong, Shouta explains that he needed to touch someone’s boobs now. Initially thinking that her grandson is just being childish, she tries to push him away, but she can’t. Instead, she notices Shouta’s erection. Does Minako’s grandson see her more as a woman and less as his grandmother?