I think this color coded mikes has been going on for years, and I only notice Aiba-chan has the green one. Regardless, I think they have specific mike for themselves. I'm no concert expert, but logically the sound technician would need to know who holds which mike and connect it to the system. I notice this when I watched V6 concert when they demonstrate how live auto-tuned being performed. How would know for example the mike A belongs to Inocchi if it's not coded? So same logic should apply to Arashi as well. Hope this ease your concern? haha... again, I'm no expert :)