Tree of Heaven (2006)

Original title: 천국의 나무

Bright and optimistic Korean Japanese teenager Hana lives at a small hot springs inn owned by her mother. When her mother decides to marry a Korean man, she tries her best to reach out to her odd, introverted stepbrother-to-be Yoon Seo, who likes to walk barefoot in the snow. He rebuffs her initial efforts, but her cheer eventually wins him over. With their parents on honeymoon, together Hana and Yoon Seo stand up to Hana's spiteful aunt Yoko and cousin Maya, and the two develop an increasingly close relationship over time. Yoon Seo is forward in his love for Hana, but despite feeling the same way, she is unwilling to break the taboo of a romance between step-siblings. After graduating from high school, she leaves for Tokyo with her admirer Fujiwara Ryu, and loses contact with Yoon Seo. 2 years later, Hana, Yoon Seo, and Maya meet again. Time has led them down very different roads, but the love and the rivalry remain the same.