There is. [One that he has created, specifically to give what was once just a bunch of disorganized monsters and absurdities enough of a common scope of knowledge that communication and a sort of shared culture and sense of values could be established.]

The supernatural has always existed alongside the world you humans are familiar with. It would have been weirder if we'd stayed a bunch of uncivilized monsters who can't even read and write while humans have compulsory education and modern schooling systems.

[They even have higher job-specific educations, standards and things like driver's licenses for youkai nowadays.]

Math is among the subjects taught, sorry to let you down. We cover a whole range of the more 'classic' general disciplines like Japanese, Science, History and PE, but there are also more youkai-specific classes like Spookology.