Unless things have drastically changed in the past month or so, and as far as I know, a two-year degree (something like an associate’s degree, or the kind of degree a person might get after two years of study at a junior college), plus some kind of TESOL certificate, is legally adequate for teaching “the official language used in the country specified in the passport of the teacher” in a cram school.
Last month I initially had trouble finding the relevant regulation, because it had been moved and incorporated into another type of document. This is what I posted last month in the way of an update (or epi-update?):