For me, Vigilante is the perfect model of slice of life and the apex of what a "casual" shounen like it can be. This manga should set an example to all those absurdly famous shounen or those that try to be like them and its own parent story could learn a lot from it.

Even when the chapters take a more episodic style, everything that happens manages to find its way into the bigger narrative and things tend to never be wasted or forgotten, even for characters that initially seem like really small ones. Mostly everything that's presented has some use for the rest of the duration of the manga instead of just being used for one or two characters to have some deeper development while everyone else are just props on a scene. That's right, characters are actually actors in the story and not only some thing hanging around in the background waiting for the main characters to give them attention. The world keeps going on even when the main characters aren't around and eventually it is shown to us, the readers, what happenned while we weren't looking. Event better, it actually makes sense for things to happen, they're not just thrown at you for the sake of progressing the story somehow.

About the characters, in short, it's something I've always wanted to see in a shounen and rarely get to see. Characters usually have great designs and sometimes have good concepts behind them, but they almost never have a proper development, not even a page can be spared for them because everything always has to be about the main character.

I'm thankful for Vigilante for having development for every minor character that appears because it actually makes the world in the manga feel more alive, like things keep happening instead of just wait for the main character to get there in the world building equivalent of Schrödinger's cat scenario. "Did something happen or is everything still the same? Wait for Koichi to open the box to find out". There's nothing like that in the manga because relevant time is actually taken to show what is going on with other characters.

Characters are the focus because they're what creates the narrative, not the other way around.

Even if it doesn't explore uncommon or greatly interesting concepts, it does deliver on what it promises and even delves in societal questions in the universe of MHA, which for some people looking for a cool shounen might not be what they want so it's understandable that it doesn't happen that often. Still, definitely one of the best manga I've ever read.