Ikkyū is a young boy training as a Zen Buddhist monk at Ankoku-ji Temple. Born in 1394 in Kyoto to Emperor Go-Komatsu and Lady Iyo, he and his mother were forced from the imperial palace due to Japan's political turmoil. At age five, he was separated from her and ordained at the temple.

He displays high intelligence, mischief, and resourcefulness, using wit and wisdom to solve problems for distressed farmers, opportunistic merchants, and others. When deep in thought or devising solutions, he habitually assumes a lotus position, wets his index fingers, and rotates them above his head—a mannerism reflecting his contemplative problem-solving approach.

In "Ikkyū-san to Yancha-hime," he undertakes a diplomatic task: reforming a spirited tomboy princess who adopts the masculine name Tsuyumaru and provokes Shogun Ashikaga Yoshimitsu by challenging him with a wooden sword. Ikkyū aims to gently steer her toward traditionally ladylike conduct, preventing her rebellious acts from escalating into political repercussions. This scenario underscores his role as a mediator, navigating delicate social situations through patience and intellectual persuasion rather than confrontation.

The film narrative maintains his core traits of cleverness and compassion while emphasizing his adaptability in mentoring another strong-willed individual, extending his problem-solving abilities from self-contained puzzles into interpersonal guidance.