Chicken Divers was originally a Muv-Luv Alternative fanfiction written by Wei Luxin.
It was officially recognized by Age and published by them during Comiket 74, the 15 August 2008, as part of a fanbook called MUV-LUV ALTERNATIVE Operation Lunatic-Dawn:Base521. Lunatic-Dawn referred to Ariake where the Tokyo Big Sight, the venue for the Comiket, was located. Base521 referred to Age's booth number.
Later, Chicken Divers was made into a visual novel which was released at Comiket 76 which took place during August 2009 (14-16).
The 30 July 2010, it was republished inside Chronicles 01, bundled with the databook MUV-LUV ALTERNATIVE LD3 Code：Rebellion. Voices were added and the production value enhanced.

Chicken Divers is a sidestory about a squadron of Orbital Divers before and during their participation in Operation 21st, the battle to take the Sadogashima Hive. The story focuses mostly on Henri Gietzen, identified as Aquila 1, of the UN Aerospace Army's 6th Orbital Corps' Aquila Squadron throughout the story, as he reminisces about his past before the drop.

[Synopsis from the Muv-Luv Fandom Wiki]