Overview
A CGI music video of Sangatsu no Lion set to Bump of Chicken's 'Fighter' single. The website states that the collaboration started because the mangaka Umino Chika is a fan of Bump of Chicken and the members of Bump of Chicken are fans of Sangatsu no Lion. A special edition of the manga's 10th compiled volume shipped on November 28 with this single.
(Source: Anime News Network)