is a Japanese adult visual novel developed by Windmill released on October 21, 2005 for Windows PCs.

A manga illustrated by Rino Fujii was serialized in Media Factory's Monthly Comic Alive between 2006 and 2007.

[3] The art director and character design was provided by Kocha,[3] and the super deformed illustrations were done by Yui Haga.

The music in the game was composed by members of Elements Garden and OdiakeS under the name Ecnemuse.

[6] Developed by Windmill's sister brand Windmill Oasis, the staff for Re:Lucks was largely the same as the original game, except for the scenario staff, which was divided between Chatora, Celery, Eiji Takashima, Hare Kitagawa and Kei Hozumi.

A manga adaptation, illustrated by Rino Fujii, was serialized in Media Factory's Monthly Comic Alive magazine between the August 2006 and June 2007 issues.

[10][11] A 12-episode anime adaptation written by Satoru Nishizono, directed by Hiroshi Hara, and produced by Artland, aired on Japan television between October 5[12] and December 21, 2006.

On January 25, 2007, an original video animation (OVA) episode was released with the first print limited edition of Happiness!

visual novel is "Zero" by Hiromi Satō, and the ending theme is "Mezame no Asa" by the voice actresses of the four main heroines (Yui Sakakibara, Mia Naruse, Yura Hinata and Oto Agumi), performing under the name Happiness!

De:Luxe is "Happiness Hōteishiki" by Yui Sakakibara, and the ending theme is "Ohayō" by Ayumi Murata.

ranked 38th in a list of "the most interesting bishōjo games"; a five-way tie with Tokimeki Memorial 2, Tsukihime, Welcome to Pia Carrot G.O.