Appearance: Long goat-like ears and red skin. His ears always hang to the sides. Five horns grow from his head. Green eyes. Wears warm-colored villager-style sleeveless clothes. Has a childhood scar on the left side of his mouth. Thick, heavy build; tall, though not as tall as Gunjo. Has a solid, weighty presence. First person: I (rough, regional) Second person: you (blunt), no honorifics A red ogre. Named Naki because he was a crybaby as a child. His mother was killed by humans 200 years ago, leading to a deep hatred for humanity. He closed his heart and acted violently, causing other monsters to dislike him, but Gunjo's mediation allows him to stay on the island. Meeting Kotake, who was separated from his brother while mushroom picking, opens his heart and fosters a friendship. He has the ability to jump anywhere by focusing strength in his legs. Though he seems crude, he is naturally kind. His favorite food is Tennyo-take mushrooms.

Appearance: Long rabbit-like ears and blue skin. His ears always hang to the sides. Three horns on his head. Dark green eyes. Wears cool-colored villager-style sleeveless clothes. Slender, tall build with an agile air. First person: I (casual) Second person: you (blunt), no honorifics A blue ogre. Separated from his mother while being chased by humans 200 years ago; her fate is unknown. He is a long-time friend of Naki, and they have great chemistry. A bit of a jokester and clever, he gets along well with other monsters. He has the ability to turn invisible. He hears a rumor from another monster about a sighting of someone who might be his mother, but he remains worried about Naki. His specialty is making himself disappear. His favorite food is Tennyo-take mushrooms.

A bitter melon monster. The mascot character of Monster Island. Lives next door to Naki. Often suffers misfortunes, such as having his house destroyed.

First person: I (feminine) Second person: you (casual), no honorifics A cat monster. The big sister figure of Monster Island. Has two tails that she can move freely like arms.

Appearance: Short black hair in a topknot. Wears clothes like Kintaro. A human baby. Wanders onto Monster Island and befriends Naki and the others. Being a baby, he can only speak simple words. Loves playing pranks.

Appearance: Short black hair in a topknot. Wears blue villager-style sleeveless clothes. Kotake's older brother. He entered Monster Island without permission to find mushrooms to cure his mother's illness, but was chased away by Naki and the others, getting separated from Kotake.

A catfish monster.