There is a couple of disturbing things about what you have written. Firstly and most disturbing is that you are seeking advice about this issue. You claim to be 44 yo and you do not understand how wrong this is?
Is it legal in your country for a teacher to have a sexual relationship with a student?
Do you want your 21yo old daughter having a sexual relationship with a 44 yo foreign teacher?
Perhaps you are one of those typical fat unattractive immature losers that is incapable of being involved in a real relationship with someone your own age from your own country, therefore you go to asia for "easy pickings".
You will get caught out, as you can be sure if you are seen with this girl the other students WILL rat on you because they are all seeking brownie points from their head teacher. Any excuse to rat on a foreigner and they pounce on it.

Maybe you should consider how you will explain this issue to your family and friends after you are deported. You certainly will not get another job in china after you get caught out.

Grow up and get a life.

And I thought I was being harsh! Anyway, Iconkiller brings up a good point. This will spread like wildfire among students, create jealousy, resentment, suspicious, and in general students will lose respect for that teacher. I had the general respect of all my students because they all new I didn't date students, and that I was FAIR and cared about them individually. They new they could trust me.