Star Fox: Farewell, Beloved Falco is a manga created by Nintendo around the summer of 2002, and part of the Star Fox series.
The manga chronicles the events between Star Fox 64 and Star Fox Adventures and, as the title implies, explains how and why Falco Lombardi left Fox McCloud's team. The manga was only released in Japan, and came with the Japanese version of Star Fox Adventures. This is one of the main English fan translation of the manga.

Some places you can read the English version from:
https://mangadex.org/title/daacd330-0267-4503-b05e-04925ddeef85/star-fox-farewell-beloved-falco
https://www.scribd.com/doc/54924929/sfa-fbf-2002
https://starfox.fandom.com/wiki/Star_Fox:_Farewell,_Beloved_Falco