The 2nd half of the show changes the theme slightly and this is most exemplified with it's villains. Most of them are outcasts and decide to do evil in this new zombie world as revenge for how they were treated by society. For most of them though, I think the deeper theme is how even just small missteps in a person's life can lead them down a dark path. Although the villains are doing truly evil things in the new zombie world and the show goes out of the way to hammer in that being "wronged" by one person in your life or "society" of course does not justify taking out your anger on everyone, it also makes sure to show most of them in a somewhat sympathetic light. I think this is most apparent with the main villain because it shows how as a kid he wasn't some monster, how as he got older he felt like he drifted away from people, and by the time he grew up he felt there was no way out. And yes he does miss opportunities to be better, but he also tries several new things to better himself. He's imperfect, like all of us. As Akira recognizes, he could've been any of us if one minor thing was different in our lives and if maybe he had someone truly reach out things could've been different. The tragedy we see at the end is that Akira tried to reach out not even knowing how much it would mean to him, but he missed the opportunity to take Akira's hand and change because he was so scared of feeling cast out like he had so many times before. I cried watching the last episode, because I recognize the evil of taking out your anger on everyone because you think it will make you happy and the simple gestures that really do give you happiness like playing in the pool with your friends as a kid.
