"Wan-wan" is the sound a dog makes
Steal human energy through selling pets
Sailor V's Striking Katana
Vol. 12 - The Pet Stories 2 - Wan-Wan's Plot
He was the older brother to both Nyan-Nyan and Chuu-Chuu. After learning that Sailor V had killed Nyan-Nyan, he sought revenge. After he himself was killed by Sailor Vs striking katana, his sister Chuu-Chuu planned to avenge both him and Nyan-Nyan. Artemis developed a crush on Wan-Wan when he was in his puppy luna form which he presumed was female but was heartbroken when he found out that wan-wan was male.
Wan-Wan was capable of shapeshifting into a dog.