Akeno is not only a mermaid, but also a "mermaid examiner". She has the responsibility of deporting all the mer-people who fail to qualify as not only resembling humans but also not arousing any suspicion of their true identities; and unlike the other mermaids in the cast, Akeno is capable of suppressing her mermaid transformation, for brief moments, after coming into contact with water, having trained herself to do so. When first introduced she had a hostile attitude towards the other major protagonists.
Akeno is a mermaid who also serves as an examiner for mer-people. Her task includes removing those who do not pass as humans and are not suspicious of their true nature. Unlike other mermaids in the cast, Akeno can temporarily suppress her mermaid form after being exposed to water through training. Upon first appearance, she showed hostility towards the main characters.