This takes place a while after the Mephyland incident. Rin notices a strange black tattoo that glows a faint blue when he's near demons. Yukio finds out and tells him the meaning of the 'totally cool' tattoo.
After finding out that Rin is actually the son of Satan they all start treating him terribly. Amaimon, who has been dating Rin for quite a while offers to let Rin move in with him which he reluctantly agrees to. He then moves to Gehenna with Amaimon away from the exorcists and any other humans. Read to find out what...