In 20××, Japan officially introduced the "polyandry system," in which one wife may legally have up to two husbands. However, sexual relations are permitted with only one of the husbands as a rule. Kaoru deeply loves his wife JULIA, but sexual duties are assigned to the other husband, Tooru. Immediately after exchanging words of love with JULIA, Kaoru is forced to watch Tooru engage in passionate sex with her. This unusual relationship—two husbands, one wife—gradually warps over time, disrupting the balance of their household.