So apparently, the anime decided not to have Rulebook dude introduce himself outright, so there’s a joke that doesn’t really come across as clearly in the anime as it does in the manga. Not that we translated it anyway.
Basically, in the scene where he talks about his ancestor, he ends it with “seigi da ze”, or “that was/that is/it is/I am/etc justice”. And his name is Seigi. Which means justice. Clever, I know. In the manga, when Kiri replies “What justice?” he just says “What are you talking about? I’m just introducing myself.”
Here I don’t think you actually find out his name until police girl mentions it.
Anyway, now that you’ve possibly spoiled yourself, here’s the episode:
Episode 04: Torrent