How do you get to the undernet in Megaman white virsion

You must first have a Tally from one of the Tora jobs. Go to Beach 2 and talk to the purple navi guarding the warp point. This will lead to HadesNet where you'll need to have Press equipped in the NaviCust. And suddenly, you'll be Undernet 1. Just like that. Magical, isn't it?