Dylan Yuki, known as Setsu Yuuki in Japanese, serves as a central human character. He is 13-14 years old during the depicted events. Physically tall and handsome, he has brown hair, blue eyes, and fair skin, often wearing a demure expression. Initially slim, his build evolves to become leaner and more muscular as he ages.

A smart, quiet bookworm and honor student, Dylan frequently reads books of various sizes. Academically strong, he aspires to be a novelist. Though reserved and calm, he demonstrates a willingness to help friends, even when it causes him personal embarrassment, and holds a specific aversion to eating green peppers.

His romantic life forms a significant storyline. Both Kaede Minami (Katie) and Azumi Hidaka develop strong feelings for him. Initially finding their rivalry annoying and childish, he gradually grows fond of both, recognizing their attractive qualities, and becomes genuinely torn. This conflict intensifies when childhood friend Haruka Morishita confesses her love. After Dylan spends time with Haruka, Kaede believes he has chosen her. However, Haruka voluntarily steps aside upon recognizing Kaede's deeper connection. Dylan then reflects deeply, contacts Kaede to meet at a park, requests she bring a watch, and formally confesses his love, which she accepts, establishing them as a couple.

Partnered with the fairy companion Rima (Rirumu), his muglox fairy, Dylan's primary narrative focus remains his human relationships and personal growth. His character development shows progression from a passive observer of romantic rivalry to someone capable of introspection and decisive emotional action, culminating in his proactive confession to Kaede.

In the manga continuity, after becoming a couple with Kaede, their relationship encounters new challenges with the introduction of another rival, Ryo Sanada, extending the exploration of their romantic dynamic beyond the anime's conclusion.