A scorching hot summer day. While her sister and her husband are away on a trip, Yukie comes to stay with her nephew, Tetsuo, for three days and two nights to look after him. Tetsuo has always had a crush on the beautiful Yukie, who exudes adult sexiness, and is filled with anticipation. Aroused by Yukie's sweaty, soft skin, Tetsuo can't help but embrace her. To appease her young nephew, who is at an age when he is in heat, Yukie agrees to do it just once, but Tetsuo, who is a virile man, can't stop himself and ejaculates inside her vagina...