This arc is absolutely horses**t. Let's see where to start.
1) It's established in the arc that trying to nick the "main group" money get you tokyo-bayed. Kurosaki did it twice scott free. Katsuragi didnt seem to get any flak whatsoever. Kurosaki frequently rent temp offices for his gigs. You always need mad paperwork for those. It's incredibly easy to trace the notes back to them and then either to Katsuragi or Kurosaki himself. Organized crime gangs are not morons.
2) Kurosaki called the cops on Watanuki. This, as Katsuragi noted, would destroy the entire ecosystem because the legal ramification fallout would make it hard for other groups to make money. Katsuragi strangely dgaf.
3) The deus ex legendary promissory note forger, despite his capability to flood the market with forgery and is always willing to do a commission, isnt known to cause any impact on the economy whatsoever. Kurosaki's trick this time wouldn't work if not for him. If such an extraordinary person actually exist promissory notes would never be trusted at all whatsoever. Especially not among underground establishments, which definitely should be aware of his existence if not involvement.
4) The goons from the "main group" got duped by the deus ex legendary promissory note forger but blamed Watanuki for it. It's like blaming drug stores for selling whatever med you chose to overdose on.
5) This bar serves presumably raw squid to nonexistent customers. THEY STINK! WHAT KINDA BAR WOULD DO THAT? WHY?!