How do you get to under square in Megaman Battle Network 3 Blue

This is only possible with the NaviCust program "Blackmind" equipped. In Undernet 3, start in the direction of the battle with FlamMan, but take the solid line of arrow paths away from the correct destination. Go up to the purple navi, and he will let you go through. Proceed, zip around the arrow paths, and enter the square.