Aogaeru is a frog spirit, wearing a blue kimono that works at the bathhouse under Yubaba. Similar to the majority of bathhouse employees, he has a very greedy personality.
When he sneaks back into the bath room at night to try picking more gold left behind after the River Spirit incident. He hope to find gold stuck in the cracks of the floorboards. He is subsequently consumed by No-Face after being enticed to walk up to him with some fake gold. No-Face's assumed Aogaeru's voice after consuming him.
His jumping into Chihiro's face while greeting Haku causes her to fail at holding her breath while they cross the bridge leading to the Bathhouse. When he yells that there is a human, he is promptly suspended in mid-air by Haku's magic for a moment while he and Chihiro escape to the back of the bathhouse. He is released soon after and runs to report the breach.
Aogaeru is the first of three spirits to be devoured by No-Face, but is freed before the end of the movie as No-Face leaves the Bathhouse to follow Chihiro.