Phantom Mother Forbidden Mother and Child Swap Creampie Sex Consultation Room for Carnivorous Parent and Child

My younger sister, Riko, has been having trouble feeling close to her husband lately, so she came to my house to talk about it. After I gave him various advice, he went home looking refreshed, but Rico is naturally shy and I'm a little worried. Then, my son Takashi arrived. Takashi, who had apparently heard our conversation, told me an idea to help Rico with his shy personality. That's something I never expected...