Zazie the Beast

The most mysterious of the Gung-Ho Guns. His portrayal in both the anime and manga are drastically different.

In the anime, Zazie uses the identity of a young boy named "Beeb" as a disguise. He can control sand-worms with a high-frequency device he wears on his head.

The anime never exactly gives a clear explanation as to what Zazie was. It can be theorized that Zazie was a malevolent entity that took control of the boy whenever it needed to, that he was in fact a much older man who only looked like a young boy, or that he was actually a child assassin driven to the brink of insanity by his association with the Guns.

Manga:

His Gung-Ho Gun number is 12 in the manga and four in the anime.

(Source: Wikipedia, edited)