I'm not sure specifically as there could be many things named 'mad dog side story'. It might be about a character nicknamed 'Mad Dog' and his adventures or side events that are not part of the main story. Without more context, it's hard to say exactly.
The mad dog in the novel could symbolize inner turmoil or primal instincts. It might stand for the characters' repressed emotions or the lurking danger that they have to confront.
The'mad dog' might symbolize inner demons or primal instincts. It could be a metaphor for the characters' repressed emotions or urges that threaten to break free. Also, it could represent an external threat that the characters have to overcome to grow and evolve.
Since I don't have much information about 'mad dog side story', I can't say for sure who the main characters are. But it's likely that there's a character associated with the'mad dog' in some way, maybe the owner of the dog if it's really about an actual dog, or the person who is called 'mad dog' if it's a human - centric story.
Overall, the characters in this manhwa are well-developed. They have their own dreams, fears, and motivations that drive the story forward. For example, the main character shows great determination and growth throughout the plot.