Shizu

Shizu is a young man with a great talent for swordsmanship. He travels in a dune buggy with Riku, his talking dog companion. In the anime, he only appears in one episode but he appears in multiple stories just about him and Riku in the novels. Riku narrates all but one of these stories. Later in the novels, Kino and Hermes meet up with Shizu and Riku again but Kino only seems to remember Riku's name. Shizu is the son of the hedonistic king in the sixth anime episode.

(Source: Wikipedia)