Seven Doors

Shishya is a young boy from earth whose greatest struggle is securing his daily bread but he finds himself reincarnated into a novel, Though he would have preferred to have reincarnated into an eroge, he finds himself reincarnated into the worst of them. 'The Seven Doors of Transcendence', in which destruction of the world is imminent but how did he end up here?Similar to shishya, there is karan who is native to this reality, he is framed for a heinous crime and sent to Narak, but the forces who used him as a scapegoat didn't knew that their very lamb will become a terrifying weapon against them for the same entity who was responsible for reincarnation of shishya. What does that entity want from Shishya and how is he connected to karan?How will they stop 'that' incident?