Tsuma ga Ninshinshita Node Dōkyochū No Gimai no Nikutai o Katte ni Tsukatta Hanashi Mo-shon Komikkuban The Motion Anime

The wife of the main character is pregnant and temporarily cannot have sex with him. However, he suddenly has a sexual desire that needs to be released somewhere. It's so good that his wife's younger sister Karin-chan also lived with the hero. She gladly agreed to sleep with the main character and thereby satisfied all his sex needs...