Elf Princess Ren.

Gou has woved to find the legendary treasure of Salamander. Searching for it he meets Ren, a fairy, who is looking for the four treasures of Heart. Gou's childhood friend Mari is frustrated with Gou running after treasures, but befriends with another fairy Rin. Gou and Ren's treasure hunt messes with a secret project led by Mari's father. It turns out Salamander isn't what Gou thought it was in the first place...