The Heirs (ABS-CBN)

The Heirs is one of the most successful drama. Its all about friendship, family, school, rivalries and young love of high school life. 

The story follows a group of rich, privileged, and elite high school students as they are groomed to take over their families' business empires. These wealthy students seem to have everything under control, except their love lives. Kim Tan(18) is a handsome and wealthy heir to a large Korean conglomerate who is sent to study abroad in the U.S. Kim Tan bumps into Cha Eun-sang (18), who has arrived from Korea in search of her older sister who claims that she is in need of money for her wedding. When Kim Tan's fiancée, Rachel Yoo, arrives to bring him back to Korea, his heart is torn between love and duty. Both Eun-sang and Kim Tan return to Korea, only to meet again. 

Slowly, he finds himself falling for her, later realizing that she's the daughter of his family's mute housekeeper. Meanwhile, Rachel's future stepbrother and Kim Tan's former best friend, Choi Young-do (18) (who also go to the same school as Kim Tan and Eun-sang) starts falling for Eun-sang as well. Troubles arise as the heirs realize the differences between money and the real world. 

source: http://en.wikipedia.org/wiki/The_Heirs_(TV_series)