Mother's Hobbies: A lewd secret from a knitting mother

My mother, Sayuri, who was holding a knitting class, liked her son Tatsuro. My mother smiles gently and knits with a smooth hand. However, Tatsuro was dissatisfied with her mother's friend learning how to knit. One day, Tatsuro goes to a friend's house to pick up her mother who taught her knitting, and sees the two of them playing with each other in an abnormal way. And Tatsuro, who can no longer contain his jealousy towards his friend and desire for his mother, impersonates him as a friend and hugs his mother from behind...