| Cosmos no Sora ni | |
 The cover art for Cosmos no Sora ni featuring heroines (clockwise from the top) Uiko, Haruhi, Suzuka, Wakana and Hiyori. | |
| 秋桜の空に | |
|---|---|
| Genre | Drama, Romance |
| Video game | |
| Developer | Marron |
| Publisher | Hobibox |
| Genre | Eroge, Visual novel |
| Platform | Windows |
| Released |
|
| Light novel | |
| Cosmos no Sora ni: Nanazaka no Mon | |
| Written by | Takei Tōka |
| Illustrated by | Rei Izumi |
| Published by | Softgarage |
| Imprint | KSS Novels |
| Demographic | Male |
| Published | June 14, 2002 |
Cosmos no Sora ni (Japanese: 秋桜の空に, lit. In the Cosmos Sky) is a Japanese adult visual novel developed by Marron that was released for Windows on July 27, 2001. The story is told from the perspective of Yasuomi Nīzawa, who discovers more about his childhood memories as the high school cultural festival approaches. The gameplay in Cosmos no Sora ni follows a branching plot line which offers pre-determined scenarios with courses of interaction, and focuses on the appeal of the female main characters by the player character.
Sales for the game were decent, if unremarkable—the game charted at number 12 in the sales ranking at the time of its release. The game is important to otaku culture and anime in general because Haruhi Sakuma is considered to be one of the first tsundere characters. Light novels, a comic anthology and audio dramas have been produced based on Cosmos no Sora ni.