An anime adaptation of the Monster Strike mobile game by mixi. The protagonist, Ren Homura, returns to the town of Kaminohara, where he once lived. But did he really live in this place before? A nagging feeling tugs at his memories. Meanwhile, a strange game is forcefully installed onto his smartphone - a game called Monster Strike. A gauntlet of battles await him. Through the fierce fighting, he pieces together his scattered memories while uncovering the truth of the game. He's supported by his companions: Aoi Mizusawa, Akira Kagetsuki, and Minami Wakaba. Together they take a step into the unknown, unsuspecting of the secrets hidden below the surface... (Source: Crunchyroll)

Second part to Monster Strike 2. 
Ren and his friends race to save the world from the apocalypse prophesied by the monster Nostradamus. When Mana discovers the truth about her origins and her role in the events to come, she becomes the key that could change everything...for better or for worse. 
Unlike its predecessor, The Fading Cosmos is not animated in full CG, returning to the 2D/CG mix used in the first Monster Strike season.

- 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)

Rinto Dead Rabbits Ltd.