When the Sun Shines (1990)

Tin Kai-On moves to Hong Kong from his hometown and initially resents his father's new wife, but gradually comes to accept her. Kai-On lives with his cousin, who dislikes him, and befriends his cousin's sister, who is tomboyish. Kai-On also has a crush on his neighbor, who initially rejects him. Kai-On, his cousin, and a childhood rival eventually become close friends and start a successful business together.