Late responder here, but my take on it. It is, as previously mentioned, a very "world building" focused novel. The main only shows doormat in the first chapter and after a good cry gets over it. Essentially, as mentioned, he isn't so much reincarnated as he is imbued with memories of a college graduate from Japan.
He does have some honor or principles It mostly in the form of loyalty to and protection of companions He isn't above revenge spoilerHope that helps