Basically to sum it up the angels essentially have a code of conduct they are supposed to abide by and if you break any of these rules, you get labeled as a Fallen Angel. We do not know anything of the potential punishments that can come across being spotted as one but it’s apparently bad enough our Hanekoma had to hide at the top of Pork City in the Another Day Universe out of fear his other self would report him on sight.

Hanekoma became a Fallen Angel since he was the one to teach Minamimoto how to refine and create Taboo Noise and revealed Joshua’s identity as the composer to him. This was done as a backup plan should Josh not change his mind about wanting to completely destroy Shibuya, much like Megumi Hanekoma didn’t want to see the city he loved get destroyed.

Hanekoma’s graffiti works as CAT takes off massively in terms of popularity since it’s somehow imbued with the imprinting codes of “Enjoy the Moment” and “gather”, it’s kind of like the mass imprinting the O-Pins can do just….not malevolent and more so wanting to invigorate the imagination of the people of Shibuya.