The end of the world, and happy birthday

The end of the world, and happy birthday is a Japanese adult visual novel which deals with an apocalyptic prophecy in 2012.

The player controls Kazuomi, a young man who wholeheartedly believes the rumor circling around online that the world will come to an end on September 29, 2012. An intensely proactive man, Kazuomi decides that he must immediately take measures to ensure the safety of Iri Chigasaki, the younger sister of his late best friend, Touya, because ever since Touya died in a motorcycle accident two years prior, Iri has mistaken Kazuomi for him due to her near-blindness. When Kazuomi's classmate Mikaeru Nagoshi also hears about the world-ending rumors, she starts a club at school to investigate them and enlists Kazuomi. With the prophesied date fast approaching, Kazuomi and Mikaeru move quickly to protect the ones they care about, with unforeseen consequences.

Depending on the player's decisions throughout the game, the story may branch into different routes and result in different endings, though there is only one "True End".