Duel

In the world similar to ours technology-wise where magic and other stuff like that is nothing but childish fairytales, Riot is just a generic, laid back student who doesn't care much about things in life. That is, until he accidentally stumbles into a hidden spirit temple and is challenged to a duel of honor by the Guardian of the temple, who is a conventionally attractive angel named Hasterien. Would you guess, Riot purposefully looses the duel so he essentially has to visit the temple and the handsome guard once again. Temple's keeper, Vieva, isn't happy about it At All, though.

Riot gets to meet the temple's spirit, a creature that is an artifact that gained sentience, a whole hidden world behins the city he grew up in that is infested by spirits, non-mortal creatures and different groups known as "Exorcists", who do their best to keep the magical side of the world hidden from mundane life of mere civillians, like the one Riot was before. Becoming an exorcist Affiliate is exactly where everything starts to go sideways -- apparently nothing is what it seems, and Riot finds himself amidst a battle he cannot win.