青春不安和躁动洋溢着的校园，情绪不分昼夜地沸腾着，每晚男生寝室总会很热闹，兴奋地讨论着关于性的各种话题，处于青春朦胧期的他们对性有无限的好奇和向往。“三年来只是亲嘴，麻木的嘴巴硬到像鸡的肾一样。”经历困难走到一起的情侣恩植（任昌丁饰）和京雅（宋智孝饰）本来就是校园里的一大新闻——因为女方不仅是s形曲线的校花，还是游泳部里有望成为国家代表选手的一号种子，而男方只是一个没有特长、平平无奇的k-1俱乐部的主席。三年来亲密的关系只维持在亲吻的尺度上，恩植屡次想和女友发生进一步的关系都失败，无奈的他只能把血力旺盛的身体用在训练上。另一方面，京雅因太爱男友反而疏远了他。游泳部最顶尖的选手京雅和前途缥缈的恩植的恋爱不被外界看好，但是只能每天在图书馆里呆呆地观察和研究女生的恩植相信爱情。他甚至有时被女友拳脚相加的痛扁也没有怨言，被朋友戏称为“21世纪最后一个纯情男”。

Eun-sik tries to pass the state exam while studying in college after his military service. One day, he meets a beautiful woman Eun-hyo, and his life changes.

The lovely and promiscuous textile professor Eun-sook has all the male professors wrapped around her finger. It also helps that she has slept with most of them. Eun-sook is also a member of an environmental awareness group. When the popular comic book artist Suk-gyu joins the group, he arouses the jealousy of Mr. YOO, one of the other member who fears that Suk-gyu will steal Eun-sook from him. It turns out that Eun-sook and Suk-gyu attended the same junior high school where they share a secret and tragic history. Back then, Eun-sook was Suk-gyu's older brother’s girlfriend. But after Eun-sook decides to sleep with Suk-gyu as well, the older brother's best friend dies in an accident in which both of them are involved. As the jealous MR.YOO starts to investigate Eun-sook and Suk-gyu's past, will their secret be kept? Will they get together again?