Hi, I'm looking for a manga I read long ago in early 2000s. The main character is male in high school age. Setting is in some prestigious medieval kind of school that resembles some haunted castle. MC is possibly a student council president from a prestigious family, smart but arrogant, who always have this monologue about being in control and hates to be controlled or coerced into anything. He has a childhood friend, also a boy about same age, kinda a goof, ignored by the MC. Until one day MC entered some alternate setting or world via a mirror. His friend got involved too at some point. Not sure how the game is but the main character had to roll dice and trade favour with some supernatural being/devil. His friend was badly injured at some point and the main character traded a tooth for it. Even during game against the supernatural being/devil, MC still has this monologue about not being controlled by them. He managed to outwit them and the friend survived. After each game in the alternate world, he will be returned to his original world. No romance at all. The only cover art i remember is the MC and a bunch of characters sitting on a long chair and the motive is mostly red.

Thank you!

maybe Kyokou no Ou