Nishikoshi was ordered by his wife to abstain from sex for a month in order to try to conceive. However, after half a month, he could no longer endure it and secretly masturbated, thinking, "I have to cum...". His sister- in-law Tsubasa found him... Frustrated by the lack of sex with her husband, Tsubasa was excited by his abstinent cock and smiled, provoking him, saying, "You've got a lot built up, haven't you?" Nishikoshi rationally suppressed his sexual desire and somehow managed to hold off until the day of the sex to try to conceive. Then, on the day of the sex to try to conceive, Tsubasa came to visit again...