One of the strengths of Welcome to Demon School! Iruma-kun is that it rarely lets anything become a one-off joke. Ameri's surprisingly demure alternate self in volume six not only makes Ronové look even more ridiculous, but it also paved the way for Iruma's transformation in volume seven, when he goes from sweet and kind to vicious and avaricious. (But also still kind.) Meeting Clara's family prepared us for Kalego's home visits to the families of his students. And Amy Kiriwo, the villain of the Battler Arc, makes a semi-triumphant return in the longest storyline in these volumes, the Misfit Class' trip to Walter Park.

While the other arcs contained in these four books are good and Kalego's does much to make him more, for lack of a better word, human as we see that he does care under his prickly exterior, it's the Walter Park Arc that does the most for Iruma as both a series and a character. It's also a very clear send-up of Disney parks in both its overly gregarious employees and hospitality, and in the fact that it has secrets out of visitors' sight. Rather than just being tunnels for character actors to get from one location to another, Walter Park is actually powered by the prison beneath it. If you know anything about Walt Disney, the man, or some of the unsavory bits of Disney history, having a maximum security prison underneath the purported happiest place in the demon realm takes on a sort of delightful irony. Children playing in the theme park are barely separated from dangerous criminals, and one of those incarcerated demons has already proven that he has no problem killing kids. Even if you don't find Amy an effective villain, it's hard to argue with how Osamu Nishi uses him here.

But more importantly, this arc really solidifies the idea that Iruma isn't a fool. He's sweet and kind, but he's also been through more than any fourteen-year-old ought to, and that doubles when you consider that it was all at the hands of his parents. Some of his kindness is innate, but other times it feels like a coping mechanism, a way to ensure that the rest of the world wouldn't dump on him as his family did. He wants to see the best in people, and that's largely worked for him, and perhaps Sullivan and Opera's care has helped him in that. But when push comes to shove, Iruma knows that not everyone is good. Offering to be Amy's friend didn't help him before, and it won't help him now, because no matter how nice Iruma is to him, the other boy is just not a good person. He's damaged in a different way than Iruma, and this is a case where never the twain shall meet. If nothing else, the Walter Park Arc shows that Iruma understands this. He has to try, because that's who he is, but he does know that he's going to be fighting against Amy and his fellow prisoners, not winning them over.

But you know who he can and did win over? His classmates. Balam may be the only one who knows his true nature (and I do love Balam despite his inability to resist snuggling his students), but Iruma's classmates are also his friends, and they're willing to do what it takes to save Walter Park. This, once again, and perhaps in more detail, reminds us that demons and humans may not be that far apart. Even discounting the fact that Iruma can hide because no one expects a human to be in the demon realm, the demons have just as much humanity as the humans do. None of them wants to see a bunch of frolicking children killed by dangerous criminals. It barely takes Iruma's lead to get everyone on board with fighting off the bad guys, because demons do know the difference between good and evil. Everyone does a lot of growing in this arc, particularly in volume ten, and it only serves to highlight the fact that the demons have been better to each other than any of the humans ever have, Iruma excepted.

It's interesting in conjunction with the evil cycle idea that demons have a time when their worst selves come out. I don't remember where I read it, but I once read someone say that PMS stood for “premenstrual syndrome” rather than “permission to manifest self,” and that may be the best comparison for it. (Yes, the nature of the evil cycle does still feel like a menstruation joke.) It's a time when the demons can just be their worst selves for a bit, and magically brought on or not, it's probably what allows the demon world to function as a society. Sure, everyone has bad days, but having a time when you have permission to be at your worst for a bit is probably very freeing – and it seems to suggest that demons like Amy don't have the self-restraint or self-control to function in normal society because they can't control their evilness. Nishi really doesn't just throw worldbuilding and plot points out for no reason, after all, and I think we can expect this idea to resurface again later.

Welcome to Demon School! Iruma-kun continues to be a remarkably strong series in these volumes. Building on earlier information and seemingly throwaway comments and characters, the story continues to delight as it pushes its characters to develop in meaningful ways. It's well-written and fun.