He produced independent films in high school[1] and when he graduated from Nagano Prefectural Matsumoto Misuzugaoka High School, he wanted to be a music teacher but gave up on higher education due to being out of work, so he got a job at Shin-Ei Animation in 1986.
The first time he was involved in scriptwriting was for the TV special Sekizō no Ongaeshi da zo, which aired on December 25, 1998, and also served as its storyboard artist and unit director.
The reason for this award is that his first original work Girls und Panzer was picked up by various media outlets as an example of "town revitalization through anime", and his versatility in creating a wide range of projects, from gag anime to serious works and adolescent dramas, as well as writing lyrics and music himself.
On the other hand, it can be said that he is so dexterous that it is difficult to see his creativity, but Mizushima's auteurism lies in the spirit of service that focuses on the customers, which has broken through to a level that no one else can imitate.
[2] In October 2022, Kadokawa announced an original anime television series directed by Mizushima titled Train to the End of the World, which aired from April to June 2024.