A fragile child with a small white body and a cute appearance. He is timid, cautious, and prone to tears, but when a crisis strikes, he shows his bravery by picking up his weapon with trembling hands to fight for his friends. He mainly uses onomatopoeia or exclamations like "Yaat..!" or "Huet?", and only uses actual language when expressing his emotions very honestly.

A child with a cheerful personality, a positive outlook, and a pure heart. He is versatile and sociable. He can translate Chiikawa and Usagi's onomatopoeia into spoken language and is often seen being close with Chiikawa. Thanks to his sociable nature, he is kind to everyone. Unlike Usagi and Chiikawa, he communicates through speech, though he occasionally gets tongue-tied or makes slips of the tongue.

A free-spirited child with a highly unpredictable 'my pace' personality. He seems to lack situational awareness, often doing things like eating souvenirs in the middle of a crisis, but in battle, he handles his staff with great skill. He mainly uses energetic exclamations like "Ura~!!" or "Yaha!". According to Hachiware, he has a loud voice and actually knows how to speak, so he occasionally communicates with words. While he looks like a mere eccentric, he is a 4D genius who shows outstanding skill in various fields.

Ranked 1st in subjugation, he is overwhelmingly strong. Called a 'Ranker,' he is deeply respected by Chiikawa and Hachiware. His reputation is so great that people flock to follow him and whisper about how cool he is whenever he appears. Naturally, he earns much more than Hachiware or Chiikawa and often buys them meals. He has a charismatic and strict personality but cares deeply for his comrades.

A diligent child with a strong sense of determination. He is kind and polite, and because he loves cooking, he follows the Chiikawa group and cooks for them. He enjoys repaying others for their kindness and acts as a supporter who stays calm even in crisis situations.

At first glance, she appears to have a cute appearance with a scale-covered lower body and a cheerful personality, but... In reality, she is the one attacking the island residents out of immense rage and sorrow over losing one of the three mermaids who were like her own children. She shows a mad obsession with finding the culprit who ate one of the three mermaids. She fights against the Chiikawa group who came to subjugate her, primarily using beautiful melodies or songs to entrance opponents or attacking with flexible tentacles.

The two survivors among the three mermaids who were like Siren's children. They have a very cute appearance. They communicate by making sounds like "Gyari-gyari." They don't seem to harbor any ill will toward the Chiikawa group.