I still don't think of Mr. Ahn as a liar. His only lie is that he doesn't have any other "students", but he is in fact fulfilling his promise of teaching Hojun about sex. He hasn't even received any form of payment so it's not like he's scamming him either. It should be a good thing for Hojun that there aren't any students.
but if I remember correctly Mr. Ahn said that he is going to sent the payment in a file to Hojun so he is in fact receiving money from him or am I wrong?
I still don't think of Mr. Ahn as a liar. His only lie is that he doesn't have any other "students", but he is in fact fulfilling his promise of teaching Hojun about sex. He hasn't even received any form of payment so it's not like he's scamming him either. It should be a good thing for Hojun that there aren't any students.