DS Navi

A DS Navi(a Dark Soul navi) is a net navi who has been corrupted by the energy of a darkchip. DS navis first appeared in MegaMan Battle Network 4 along side the introduction of darkchips.

MegaMan DS
By the plot of MegaMan Battle Network 4, MegaMan.EXE is forced to use a darkchip to defeat ShadeMan.EXE thus creating his dark soul. The entire game, MegaMan is challenged to either resist the dark soul's influence or fall into its temptation.

MegaMan NT Warrior
DS navis are essentially the Darkloids under the control of Nebula