Without knowing much about the show, you might take a look at a picture of Nanbu from Megalo Box and think he’s kind of a terrible person, and this is not entirely wrong. Nanbu is very much a wolf in sheep’s clothing, even despite how obvious it is he is a wolf. He spends a lot of the show pretending to help JD, only to betray him afterwards.
In the show’s most recent episode, Fujimaki, the man supporting Nanbu and Joe in their efforts to reach Megalonia, reminds Nanbu that they are not there to win. The only reason he decided to support them in their efforts to reach Megalonia is to force Joe to throw the fight so that Nanbu could pay off his debts to them. When Joe finds this out, he gets rightfully angry, questioning whether or Nanbu even thought he could win.
Fujimaki goes on to describe Nanbu later on as a scorpion, and compares him to the main character in a story about a scorpion who needs to cross the river, only to betray a frog that agrees to help him. When the frog asks why the scorpion stung him, the scorpion basically replied “I had to.” However, I do not think that story is necessarily the most accurate description as a whole.
For starters, Joe throwing fights at the beginning of the show was the only real way that he could make money while fighting and not get caught. Even despite his manipulative behavior while managing him, Nanbu was in a way helping him by letting him fight while making sure he was ok. Without the money he got from fighting, JD could have ended up homeless, and possibly dead. It would not be the easiest surviving as an undocumented person living in a big city.
It is also important to remember that Nanbu’s training is a large part of the reason Joe was even able to get to Megalonia. It is fair to say that Joe had a lot of natural talent, even before they began training for Megalonia, but there was no way he was going to make it there withoug Nanbu’s connections or his ability as a coach. This is not to say that the relationship they have during this period is not manipulative or possesive, far from it. But, it is important to remeber that Nanbu is not just a bad person.
Again, none of this is to say that Nanbu is a great person, or even a good person, but like every character, and even just like with people, pointing out only the good or only the bad in someone will never give you a wholistic view of that individual. Doing good does not negate doing something bad, and vice versa.
What do you guys think of the Nanbu as a character? Let me know in the comments below. Also, if you want to support the Aniwriter through donations or are just feeling generous, consider buying me a coffee on Ko-Fi. Otherwise, thanks for reading and bye for now, Friendos!
Animated Observations 
I don’t think Nanbu is a total jerk; the flashbacks seemingly show a different man from what we see in the current day. I think he’s a good character because he’s in the moral and ethical grey area.
I think you’re being a little toooo lenient on his handling of Joe, though. Joe could very well still have fought illegally with another trainer/promoter, or hung out at the one guy’s shop he returns to after his falling out with Nanbu. There’s no guarantee he’d be dead or homeless. Nanbu is pretty much the entire reason they’re in trouble in the first place. Sure, he’s a decent trainer, but he became an alcoholic after he thought Aragaki died, and ultimately used Joe to subsidize himself while he acquired more debt from drinking and gambling.
He isn’t really malicious in his intent, but he is entirely selfish. In looking out for himself, he dragged both Joe and Sachio into harm’s way. The multiple dimensions to his character make him interesting, but at this point, it’s hard to give him a whole lot of sympathy. I reckon he’ll slightly redeem himself here at the end, but he and possibly Joe are still probably going to end up dead.
LikeLiked by 1 person
Yeah, it’s definitely a lot easier to understand him when you take into account Aragaki. I think a lot of the reason he doesn’t trust people stems from that. Not saying that gives him an excuse, but worth noting.
LikeLiked by 1 person