After a drinking party, Nakagawa Keiko and a male friend who missed the last train stay in the same room. Even though they are friends, they are still the opposite sex... Of course, if you share the same bed and sleep together, you'll want to have sex. Nakagawa's desire is turned on as he teases her with a vibrator. Although he says he has a girlfriend, he insists that they keep it a secret... but Nakagawa thinks it's okay to keep quiet... and falls into the sweet temptation and gets sucked into a sex swamp. What is it like having sex between friends who have known each other for a long time?