"GAO" was chosen as the nickname of the Oga Aquarium as a result of a public contest held in July 2003.
(Applications: 2980 variations, 3919 in total)

Why GAO?
GAO was considered most appropriate because, standing for Globe, Aqua and Ocean, it uses the same letters as Oga, and it sounds like a roar, which symbolizes Namahage's sturdiness.

From among 18 applicants who submitted the same or similar nickname as GAO, the following three persons were selected: Fumi Hasegawa (Akita City), Mayumi Ogiwara (Akita City), and Tomoe Maeda (Odate City).

The logo was also chosen through a public contest conducted in fall 2003.

Each fish-shaped letter has an image of Namahage roaring "gao" with its mouth open.
Reflecting the meaning each letter stands for, G (globe) is colored green, A (aqua) is light blue, and O (ocean) is blue.

The logo, designed by an author of children's book Norihiro Wakahara in Tokyo, was selected from among 98 candidates.