A deeply loving and responsible man who cares for children and sincerely wishes for each one's growth. Despite being the director of the Tenshien orphanage, he works hard in the fields for the children's sake, leading by example. He is not only kind but also capable of being strictly corrective when they act wrongly, always considering their future. Despite suffering harsh treatment from Japanese people during the war, he does not hate them as a whole; he values facing each person as an individual rather than judging them by nationality. Even as his own illness worsens, he shows consideration by trying not to worry those around him. His unique finger-snapping gestures and firm handshakes reveal a bright, energetic personality. He is a trustworthy figure who combines strictness with kindness, caring for the children until the very end.

A calm, composed individual with very clear convictions. He has a passion for butterfly collecting and shows intense interest and obsession with insects, treating rare specimens with great care. His meticulous identification of collected butterflies suggests a knowledgeable nature and a desire for accurate judgment. On the other hand, when a precious butterfly is damaged, he does not explode with rage but instead adopts a cold, contemptuous attitude. His words and actions suggest he prioritizes his own values and standards, making him slow to trust others. Because he offers no sympathy or consolation, he leaves an impression of being cold and harsh. This attitude is an expression of his devotion to his butterflies and his refusal to compromise his standards; Emil is a presence who makes others acutely aware of their own immaturity or mistakes.

A pure and honest man with a strong sense of justice who cannot tolerate evil. Upon learning that the King distrusts people and is killing the innocent, he feels intense rage and acts to overthrow him. Conversely, he possesses a very human side that prioritizes personal circumstances, such as leaving his friend as a hostage so he can attend his sister's wedding. While running to keep his promise, he nearly falters and gives up due to exhaustion and hardship. However, by remembering his promise and the trust of his friend, he stands up again, determined to run to the end. This shows a strong will to strive and not flee from responsibility despite his weaknesses. He possesses the sincerity to believe in his friend and the desire to be believed in return. Though far from perfect, he is a brave man who values friendship and trust above all else.

A clever and brave fish, the only black one among his many small red siblings. He lived happily with his kin until a large fish swallowed them all, leaving him alone. Though he initially swims through the sea feeling sad and lonely, he gradually regains his spirits. He possesses the strength to move forward and look toward new things even in difficult situations. Later, he encounters other small fish, but they are hiding in fear of large predators. Swimmy uses his wisdom to devise a way for them to look like one giant fish, suggesting they work together to face the enemy with him acting as the eye. He is a natural leader with excellent intelligence and initiative, capable of encouraging his peers and guiding the group.

A mysterious entity whose true nature is never clearly explained. In the original work, phrases like "Clammbon laughed quap-quap" and "Clammbon died" are spoken, suggesting it is a familiar object of interest or concern to those nearby. However, exactly who or what Clammbon is remains undefined. Consequently, the reader must imagine its identity based on the dialogue of the crab brothers and descriptions of underwater light and bubbles. Clammbon's presence highlights a sense of a wondrous world and primitive sensations. Rather than being a character with detailed traits or actions, the very mystery of its identity creates a fantastic atmosphere, prompting reflection on the wonders of nature and the essence of life.

A lonely little fox who loves playing pranks. He sometimes causes trouble with his mischief, acting without fully considering the feelings of others. However, he possesses a conscience and a kindness that leads him to reflect on his mistakes and care for his targets. On the other hand, he is socially clumsy, unable to communicate the reasons for his actions, which leads to tragic misunderstandings. Despite his loneliness, he has a heart that understands the sorrow of others and tries to act for their benefit. Through him, the story depicts the difficulty of understanding others and the importance of communicating one's compassion.

A presence that illustrates the transition of society and human relationships through the contrast between the past and the present. In the past, Auntie Yang was bright, active, and lived in close connection with those around her. However, when reunited after many years, she appears vastly different. Living in hardship and poverty, she is depicted as coveting the belongings of others and seeking only what is convenient for herself. Her struggle for survival has robbed her of mental leeway, revealing a pragmatic and selfish side. Yet, her change cannot be dismissed simply as a character flaw. One must consider the impact of harsh living environments, such as social shifts and poverty, on the human psyche. By highlighting the difference between her former and current self, she prompts readers to think about how social change affects the human heart and relationships.