Ton Ruk

Pu's mom killed herself after finding out that Pu's father had married a second wife. Pu is left with her grandmother, her dad's mom. When Pu's dad comes home with his new wife, she dislikes Pu and tortures her as Pu grows up. However, Pu is a soft-hearted girl, so she is still very kind to her stepmother and stepsister. Pu only gets along with her half-brother because they've connected when they were growing up and have become friends. Ong was the son of Non's dad, so he also grew up and bonded with Pu. However, he went to study abroad, so he hasn't seen her in years. Ong and Pu don't know how each other looks like, so they don't recognize each other when they meet again. It's later that they both fall in love with each other. However, her stepsister is also in love with Ong, so she's not going to let Pu get him.
(Source: AsianFuse Wiki)