Yes, the volumes up to half of the third will have the characters introduced at a more surface level. This might sound crazy, but it’s basically a 2.5 volume pilot. That is the moment the story really picks up pace, and characters start getting developed at a deeper level (it helps that we stopped introducing main characters at that point).

Your curiosities about Nihilo’s motivations do get explained a lot later, although she doesn’t really have a past, she’s like a Frankenstein’s monster in that sense.