Shizuka Domeki is a high school student and classmate of the protagonist, Kimihiro Watanuki, who serves as a key supporting character in the film's events. His background is rooted in a family with strong spiritual connections, as he is the grandson of a temple priest. This heritage grants him powerful innate abilities to ward off evil spirits, a trait that stands in stark contrast to Watanuki, who naturally attracts them.

In terms of personality, Domeki is the calm and collected foil to the excitable and often frantic Watanuki. He possesses a stoic, quiet, and frequently sarcastic demeanor, rarely raising his voice or showing strong emotions. This cool and unflappable nature makes him popular at school, though he seems largely indifferent to the attention he receives. Watanuki perceives him as a rival, particularly for the affection of their friend Himawari Kunogi. However, Domeki shows little romantic interest in Himawari and instead appears driven by a quiet but firm sense of duty to protect Watanuki, often appearing at critical moments to keep the supernatural threats that plague Watanuki at bay.

Domeki's primary motivation throughout the story is the protection of others, especially Watanuki. Despite Watanuki's constant protests and hostility, Domeki consistently positions himself as a guardian. In the film, Yuko Ichihara, the dimension witch who employs Watanuki, specifically invites Domeki along for the expedition to a mysterious collector's mansion because his spiritual power makes him an effective defender. His role in the story is largely that of the protector and the man of action. While Watanuki can sense and see spirits, causing him great distress, Domeki has the power to repel and exorcise them, making him an indispensable asset when the group finds themselves trapped in a mansion where strange and dangerous events begin to occur.

The key relationship in Domeki’s life is his complicated dynamic with Watanuki. Theirs is a bond of mutual necessity that deepens into a significant friendship. Watanuki resents Domeki for his ease of life and perceived coolness, but Yuko has told him that staying near Domeki repels the ghosts that constantly harass him. Conversely, Domeki sees Watanuki’s suffering and, in his own quiet way, takes on the role of a protector. This is not a one-sided arrangement; Domeki will often request elaborately prepared homemade lunches from Watanuki as a form of payment or exchange for his services, a dynamic that highlights their strange but functional partnership. He also has a respected connection to Yuko, who recognizes the purity of his spiritual energy.

Within the specific story of A Midsummer Night's Dream, Domeki does not undergo a significant personal transformation, as the film focuses more on the mystery at hand. However, his established character traits are on full display. He is the composed anchor to Watanuki’s anxiety, using his archery skills and exorcism abilities to deal with the physical and supernatural threats they encounter in the mansion. It is through his actions and his ability to see through illusions with a practical eye that he contributes to solving the mystery. His development in the broader context of the series is a gradual opening up, but within the film, he remains the steadfast and reliable figure he has always been. Notable abilities include his exceptional skill in archery, which is channeled through his inherited spiritual power. He can draw his bow without an arrow and fire a bolt of pure spiritual energy to exorcise or destroy malevolent entities, making him a formidable force against the supernatural world.