For The Painting
The question that I'm always asking myself in such stories is"Why are they even doing this? What's their point? There's no purpose for all this"
1. To rise from the complete bottom of society to the top based on merit and become a great hero of legend in the process. (Shin)
2. To end a 500 year long era of brutal warfare where millions have died and cycles of hatred have been born and perpetuated (Sei)
And every character in Kingdom is to some extent an exploration of one or both of these ideologies.