I second Foxy's advice, don't bother.

For one, the market for English centers/schools in China is saturated, both local and international private-owned schools struggle to fill in classes while public schools are overcrowded.

Beside, how do you intend to set up your school? Through that 'Chinese girl you know'? Bad idea, as per Chinese law if you set up a joint venture the Chinese partner must hold majority of the shares, anyway screw the law they can take the entire company from you and kick you out at any given time and nothing will happen to them, this is a matter of fact anywhere in China.

Plan on setting up a WFOE? Bad idea here again for Foreign-owned companies are subject to rules and regulations that are totally abusive and are basically prevented from being too successful, just because. The government will give you some seriously hard time if you own a school as a Foreigner, ever increasing regulations that no Chinese-owned school will ever have to deal with. Just because, is the key word here, no real reason but rampant xenophobia.

If you got a real interest in offering quality education then you better invest or open a school in any other Asian country, because anywhere else is more business friendly and cares more about education than China.

Besides, China is not this wild eldorado where anyone can make it big anymore and the days of rapid economic growth are over. China today appears to be slowly headed for a decades long stagnation not unlike Japan. Well, a much poorer and more dystopian version of Japan if you wish, and minus all the weeaboo things that make Japan cool.

Good luck!