Keys to the Heart
그것만이 내 세상 (original)
An older brother is a washed-up boxer. His younger brother is a genius pianist with physical disability. The brothers make up through their mother who is full of stories of her past.
Starring Lee Byung-hun, Youn Yuh-jung, Park Jeong-min, Han Ji-min, Kim Sung-ryung, Choi Ri, Bek Hyun-jin, Hwang Suk-jung, Park Ji-yeon, Moon Sook
It's a kids and drama movie, and has a rating of 7.4 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from Germany.