MONSTER STRIKE: WINTER SPECIAL - RAIN OF MEMORIES

- They deserve better. Someone better than me... - The stage is set one year before Ren arrives in Kaminohara. Akira has moved to Kaminohara from Sendai, all for the sake of revenge. The wounds that his sister suffered in an MS battle fuel his vengeance. A lost Haruma is given directions by Akira, revealing a caring side to the usually cold and calculating teen. Haruma observes Akira's violent MS battles, and realizes that Akira fights while reading his enemies' attacks. Haruma proposes the idea of recruiting Akira to his teammates, Aoi and Minami. Surprised and naturally reluctant, Aoi and Minami decide to trust Haruma. For Haruma has resisted recruiting the fourth member of their team, saving the spot for the right person... (Source: AniDB) — Description from AniList community (anilist.co).