S3OVA1 Buildup of Early Spring!

Buildup of Early Spring! (早春のビルドアップ！ Soushun no Birudoappu!) is an OVA released before the third season of the Free! anime was aired and is considered to be episode 0 of Free!-Dive to the Future-. It premiered in Japanese theaters on June 23, 2018, and was bundled with the DVD and Blu-ray releases of Free!-Dive to the Future- which were released on September 26, 2018.

Synopsis
In Tokyo, it's time for the annual High School Mascot Competition. Three students from Iwatobi High School are in town with the required life-sized Iwatobi-chan costume. They are excited, but distressed because the beak is missing. When Makoto Tachibana runs into them and they learn of his Iwatobi history, he is manipulated into wearing the costume and competing in the sumo-wrestling contest between mascots. Meanwhile, Haruka Nanase happens to find the missing beak when he accidentally steps on it. Realizing what it is, he heads to the contest venue where he meets the students and Makoto. There, he convinces a reluctant Makoto to defend his alma mater's honor, then stays to cheer him to victory.

Characters
List of characters in order of appearance: