Reincarnation of an (History) Otaku!

25-year old Japanese salaryman, Orimura Takeshi was walking home after another night of overtime when he chanced upon one of his juniors trying to commit suicide. He saved her at the cost of his own life, and when he woke up, he found himself in the body of a teenager with memories of a new life. He had been reborn as Laius Orimius Tacheus, son of a minor noble of the land of Rumalia. And using his newly granted knowledge of another world? He has come to bring an unprecedented revolution upon the land!