Use your 3DS at Antenna Tower to look around. You will see Denpa Men floating around, and you might even be surprised at how many of them there are!
Aim the reticle at a Denpa Man and press the A button to cast a net to catch it.
But beware! They’re faster than they look! The Denpa Men you catch are sent to “The Denpa Men House” in Digitown. There, you can decide which members to put in your party. Make sure to pay them a visit after catching them!