This is Igneous Karatia, Karatzu and Katie's son. He serves as one of the rivals to Kao's team, and though he seems cocky and muscle headed, he actually is pretty hardworking and outstanding who just loves to see the best in others as well as himself. He's just really outgoing and competitive, much to his father's respectful annoyance.
1. I used to imagine this guy as a pure villain to Karatzu, but in a quick character development stroke of inspiration, making him Karatzu's hard working son yet also his biggest rival helped with making the narrative for Karatia Caverns and Karatzu himself more interesting, given before this idea, Karatzu was just a parody of the cranky old man who is overly paranoid, but out of respect for my characters, I don't want anyone to be a "joke for the sake of parody" but every ounce of them to have purpose. Karatzu is still cranky and ultra paranoid, but now it's just a reflecting of his parental personality and his exhaustion, since having an ultra energetic son, he has a better reason to want to settle down.
2. Igneous is as old as Kao, but appears larger due to his muscles and tonnage. So therefore he tends to see Kao and his team as "younger" despite them being the same age. It doesn't help that Karatzu keeps calling them "Kids" but that's more due to Karatzu's age and personality more than anything and less a reflection of the team actually being "kids" (They're not in Starmaninjian terms).
3. This is ironically the situation where the kid is a harder worker than the father and the father wants the kid to slow down. Igneous always makes fun of his father by challenging him to dig out massive tunnels and build amazing construction projects while Karatzu is freaking out to the fact that Igneous hasn't rested in over a day and still has the energy to keep going at his prime. It's not that Igneous is immature or hard headed, but more so just a reflection of his competitive spirit and Karatzu being constantly tired. He is still very smart and obeys Karatzu's warnings when there's clearly danger.
4. Yes that is a 10 ton weight on his ankle. But given he is made of Rock practically...being a Caverkoya, it actually is weightless to him. He's just wearing it to show off. That's why he doesn't have one on his right leg to balance. Similarly, the cracks on the floor are caused by him walking cause again, he wants to show off his strength.
