Kunio is a supporting character in the animated film Lu over the Wall, a classmate of Kai Ashimoto in the quiet fishing town of Hinashi. He is the son of the priest who oversees the Hinashi Shrine and is expected to eventually take over that role, yet he remains focused on enjoying his youth. Among his friends, Kunio is the most carefree and fun-loving, though he also possesses a self-conscious streak and can become worried or unsettled when his personal life intrudes on his music. His greatest devotion is to music: he plays guitar and sings in the rock band SEIRÈN, which he forms together with Kai and Yūho. It is Kunio who actively invites the reluctant Kai to join the group, a gesture that sets the entire story into motion. His enthusiasm is contagious, and he often acts as a lively bridge between Kai and the other band members, helping to draw the more withdrawn Kai out of his shell. As Kai’s best friend, Kunio offers steady companionship, lighthearted banter, and genuine encouragement. He also welcomes Lu, the mermaid girl, into their circle without resistance, instinctively treating her as a friend and bandmate. Throughout the narrative, Kunio navigates personal difficulties that temporarily shake his confidence and force him to face deeper emotions, which adds a layer of vulnerability beneath his cheerful exterior. His ability to express himself through music, his skill as a guitarist and vocalist, and his unwavering passion make him a vital source of energy and heart for those around him. By the end, his consistent support and infectious love of music help the group achieve harmony both on stage and as friends, marking him as an essential presence in the unfolding story.