Ichijo Kazuya thought that he was murdered, but when he came to, he was back in his high school days. He lived his entire life as a playboy and had had countless sexual encounters with women until that fateful day that he was killed. He realizes that his murderer was his old high school friend Tanaka Masaki who was jealous of Kazuya’s relationships and his built up anger eventually exploded.
Taken back 15 years into his past, it seems that he has been given a second chance at life and given a chance to make different choices. He decides that the way to prevent his eventual demise is to make sure Masaki is more successful with girls and loses his virginity before Kazuya. But fate seems to be steering Kazuya towards the path of his previous life and keeps introducing the same girls he had sexual encounters with. (From MangaHelpers)