Pirika Usui

Horohoro's little sister, who trains him in a similar manner to Anna's training of Yoh. Pirika originally calls Yoh a jerk for defeating her brother, giving Yoh a heartache over people hating him. Pirika later becomes friends with Anna and Tamao. "Pirika" means "pretty" and "pirka" means "good" in the Ainu language. She was born on February 9, 1987. Though not shown in the manga or anime, the author has stated that Pirika's partner spirit is Torara, a Marimo or Torasanpe as said in the Ainu language. Torara was said to have saved Pirika from drowning at an early age, and since then they became partners. Torara can manipulate water, but is very shy, and for that reason he did not make a debut in the manga or anime. -From Wikipedia