Actually also dramas are ok, but the most important thing is that the child abuse is the main theme. Also it would be perfect if it's based on truse stories, or something that is the reality. It doesen't metter if it's chinese, japanese or korean.
the Crucible that's the only one I know of. I've heard it's very graphic and intense.
I can only think of dramas: Innocent Love and Mars. Autumn's Concerto also has some but it's not to a child.
Man from Nowhere. - more on kidnapping children and using them to do illegal stuff
Don quioxe!!!!!!!!!!!!!!!!!!!

PERFECT FIT.

In this unusual story, Matsuda plays a child welfare official Shirota working at a child consultation center, while Takahashi Katsumi plays a charitable yakuza boss Sabashima. These two lead completely different lives, but one day, their souls are suddenly switched. As a result, Shirota begins dispensing odd advice about the "rules of society" and other things. While his colleagues naturally see this as a problem, the children gradually come to rely on him.

8.01 GLOBAL SCORE.
King of Baking, Iljimae, Spring Waltz all have some parts if I remember correctly. Also I 2nd ^^ Mars and Innocent Love.
No One Knows, movie based on true story of abandoned children.
Yes No One Knows is really really good. But my recommendation is Kou Kou Kyoushi 1993.