Tenshi No Hane To Akuma No Shippo
Other titles :
てんしのはねとアクマのシッポ, Angel's Wings and Devil's Tail, Tenshi no Hame to Akuma no Shippo, Engelens Vinger og Djevelens hale (Norway)
Author(s) :Kiriga Yuki
From Aerandria: The story begins from the moment a young devil boy transfers to an Academy for angels located deep inside the forest. He was tasked to clean out the monsters in a nearby forest but after successfully doing so, the angels asked him to become the Academy's Knight to prevent a 'great catastrophe!' Sounds great! But, wait... a devil who's a Knight in an Academy for angels?!