Nong Miew Kiew Petch

Miew was a a nerdy girl who took dance classes with Sila. Sila only saw her as a student and nothing else. One day Miew dies and at the same time Petch dies too. Petch's spirit goes into Miew's body and Miew's spirit dies. So Petch is now in Miew's body and tries to get back to her original body.
(Source: AsianFuse Wiki)