@Protein
Like everywhere, it depends on the school he works at, if he works in a cram school he can make some bank, if he gets in a private academy he would not only make bank, but get prestige, if he works in a public school.... well thats like throwing darts.
Being a teacher in Japan isn't exactly the best paying job ever, but it's not nearly as unlivable as being a teacher in America, where you literally can't make a living and also no one appreciates you.
But yeah, this is giving very Nariyuki vibes (from ぼくたちは勉強ができない / We Can't Study / We Never Learn (the "official" english title, which is a bad translation on viz's part))
After reading 208 chapters, I'm not sure if the publisher of this manga even gives a hoot about progress. I lost track of the last time any real progress has been made. Last "progress" was more like a half step up, a half step down. Dwelling on graduating and Tokyo U is keeping this from making proper movement.