Kakugo no susume

Kakugo and Harara are siblings trained to fight the monsters roaming in post-apocalyptic Tokyo. 21st century. To aid them, Kakugo and Harara were entrusted with "Fortified Armor Shells", exoskeletons forged from the souls of deceased warriors. After Harara succumbs to the evil within the armor, it is up to Kakugo to defeat his sibling.