Zero! Is the amount of development main character makes during this show. Do you think he has issue with watching people's memories while doing his job? Don't worry, he'll tell you at least couple of times every episode. He's also your typical japanese worker staying overtime constantly even at the cost of his social life and friends which he doesn't have and show is portraying this as a virtue constantly praising how he achieved all of that by staying late at night. All that said, show is interesting and story holds up well. It's a little bit disappointing that you can't figure out things on yourown because they are hiding a twist every time. Whenever there's no twist it's painfully obvious who the culprit is but they are still treating it as a mystery. At times they pull CSI level of bullshit like zooming in on retina reflections and stuff, but it's not frequent enough to be a distraction.

Aside from main characters seeing no development over period of what feels like years, show is well worth watching. Animation and art is great, audio is not bad either. Characters are downright retarded and have no ability to learn or understand anything. Mystery at times is not a mystery but at least stories are creative enough to keep your attention high. If this is sort of thing you can accept, definitely worth a watch.