The second season of Monster Strike. 
 
Monsters are just a daily fixture of life these days. Ren, Aoi, Akira, and Minami have taken it upon themselves to clear the neighborhood of violent monsters. Days pass, until a transfer student from America, Mana Livingston, appears in their class. Mana quickly becomes a friend as the gang bond over their monsters. But a creeping shadow begins to lurk in the darkness, a harbinger of the danger to come. A new chapter of Monster Strike is about to be written! 
 
(Source: Crunchyroll) 
 
Includes episode 0.