DS Navi

A DS Navi (Dark Soul Navi) is a NetNavi who has been corrupted by the energy of a Dark Chip. DS Navis first appeared in MegaMan Battle Network 4 along side the introduction of Dark Chips.

MegaMan DS
By the plot of MegaMan Battle Network 4, MegaMan.EXE is forced to use a Dark Chip 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.

Battle Chips
When a DS Navi is defeated (or when achieving the specific busting level against an SP Navi), MegaMan will receive that Navi's DS Chip. DS chips, like Evil Chips, can only be used by dark NetNavis.