Renraku also has Najima Securities. But I think that they amount to mall cops. While Najima is a town in Japan, Najima Securities is a North American subsidiary.
What you have to watch out for is Armada Personnel. Najima and the Red Samurai are dedicated security personnel. But Armada provides stuff like secretaries, truck drivers, temps, etc. What you don't really notice is that Armada also vets their personnel... and the personnel going into other Renraku subsidiaries. What that means is that they do deep background checks and also provide executive protection and provide other less public assets. You see Najima and the Red Samurai, but the tendrils of Armada are invisible and insidious.