Yuuto has a specific fetish that prevents him from getting aroused unless he’s with two busty women at once, causing problems in his marriage to his childhood friend Sae. To solve this issue, Sae invites her friend Emi to join them for a threesome arrangement to help them conceive a child. During their first encounter, Yuuto experiences intense arousal from being with both women simultaneously, and they establish rules including that he must use condoms with Emi and save his creampies for Sae. The arrangement continues with Emi visiting for sleepovers, though Yuuto eventually convinces both women to let him have unprotected sex with Emi as well, leading to increasingly passionate encounters between all three of them.