Ok maybe I missed it but how old exactly is Si-eon?

Ehm it was not mentioned but I guess 35-37 or maybe 40 lol.

Oooh so it really wasn't mentioned

And the student? How old is he?

But by the way Namwoo said "you should be glad I'm going knowing that" (his age) , might be because there really is a huge age gap between them. So he might be in his forteen or sum like that

If I remember correctly in his twenties. I think it was 26

Thanks