This is a shonen-ai or a yaoi. It's about a regular teenage boy Yuri Shibuya who is going home from school one day. He runs into a scene where a school friend of his is getting bullied. He stops the bullies and ends up getting a 'swirly.' Not any ordinary swirly but one that gets him sucked down into a demon dimension! ^-^
When he gets there he is mildly confused and thinks that he is in an amusement park. He sees a local girl and tries to speak to her and she starts speaking a foriegn language! All the villagers start throwing any and everything at him. A man by the name of Adelbert von Grantz cast a spell on him that allows him to understand them. Conrart Weller, or Conrad saves him.
He takes him back to the demon castle where he meets Wolfram, Conrad's younger brother. He ends up slapping him on the left cheek and now they're gettin' married.
