A busy trading-company employee spends most evenings eating alone because his managerial wife always puts work first. When she does come home, she uses him for rough stress-relief sex until he is exhausted. Her adult sister Azu often visits after seeing how strained the marriage has become. Their conversation turns to sex, and Azu mischievously plays with his crotch before whispering a deal in his ear: if he can go 30 days without ejaculating, he may do anything he wants with her. When his wife leaves on a business trip, he finally empties his pent-up load through intense sex and repeated creampies with Azu.