"I thought you said he was the stupid one!"
--Negative Numbuh 3
She is the un-emotional and theoretical opposite of Numbuh 3. Unlike Positive Kuki, Ikuk has no obvious feelings for Eeballaw or Positive Wallabee, saying almost immediately upon meeting Wallabee, "I don't like you."
When Ikuk arrived, she carried a device that resembles to T.H.U.M.P.E.R. but the 'ammo' appears mad and evil.
Apparently Eigin thinks highly of her (or perhaps is simply just scared of her), because when positive Wallabee crashes her against the wall, he says, "Y-you can't talk back to Negative Numbuh 3 like that!!!" Like the other negatives, Wallabee was only able to tell it wasn't her positive counterpart because he could see the evil in her eyes that aren't in positive Kuki's.
The Negative Sector V was sent the Positive Universe to replace their counterparts and open a portal to their world at the public pool, where they would kidnap kids to work in their world. At first, Positive Wallabee, being dumb, was initially fooled but upon looking Ikuk in the eye, he realized they all were from the Negaverse. Ikuk then attempted to recruit him, believing he'd be stupid to refuse. Naturally, Wallabee refused and beated Negative Sector V back to the Negaverse, where he undermines Eeballaw's authority by calling him a coward. Following this, Ynnaf compelled the DNK to turn again Eeballaw and when he turned to Negative Sector V, they too abandoned him. After Negative is sent to his broccoli mines, the DNK reforms and vows to remake their world into a better place.