Gaako is a freshman student attending Barbirus Demon School in the same cohort as Eiko.
Gaako's form is that of a green dragon with purple eyes and wears the school female uniform.
Gaako is shown to be calm.
Eiko Oni - She is Gaako's best friend.
- Gaako appears only in the anime series, not in the manga series. However she does appear briefly in chapter 152.