How to change HIDDEN_NPC sprite?

[cruemantin]

Title says it all, how can I chang or replace this particular sprite? "http://nn.ai4rei.net/dev/npclist/?q=111&qq=search" (link is for reference) NPC ID: 111 Name: HIDDEN_NPC. My problem is that I can't locate it on my server files and I can't replace it with a larger NPC sprite. I want it to be visible instead of being just hidden. Any help will be appreciated thanks!