tv tropes whose line

Langit, an ordinary teacher, died in an accident. He wake up in a new world Valandria, but to his surprise, not as Hero or even as human, but a skeleton. He was reincarnated in a catacombs full of undead and creatures of darkness. The catacombs itself was just a small part of Magna City, a cursed city that become nest for monsters, ghosts, and curses over the ears, as well as the most dangerous place in Valandria. With a guide system he called The Narrator, Langit started his second life in never-ending struggle to survive and to reach the highest level possible. But before that, to celebrate his new life, he changed his name to O. Yes, just one alphabet: O. A letter similar to number 0 (zero); a philosophical symbol that he would start his life again from zero. Whatever happen in this new life, he can't be like his weak, old self. Can O survive in this life, or more importantly, to be at the top of evolution? Enjoy his struggle to become the strongest as he unravel the secrets of the cursed city!