Imawabi no Dakini

Fushimi and Toume were just a normal boy and girl going to high school until one day they stumble upon a phantasmal mountain known to legend as "Mount Hagure" . Before either of them knew it, Toume was possessed by a Yoko named Dakini, a goddess who grants wishes.

When asking what Fushimi's wish is, it is only this: Give Toume back. Dakini says she can grant the wish but in return he must become her servant. The deal is struck. Fushimi has now become Dakini's servant and Toume has been returned. Darkness, however, is afoot and now Fushimi must take on a more active role as Dakini's servant. Is he up for the task?!
(From: MU)

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