Hailey Anne Thomas, known as Ana Thomas in select regions, is a human character in the Yo-kai Watch series. As a fifth-grade student in Class 5-1 at Springdale Elementary School, she shares Nate Adams' age. Her distinctive appearance includes short purple bob-cut hair, large round glasses, and dull purple eyes. She typically wears a blue top with a yellow music note, a pink cardigan featuring striped hems, a white miniskirt, dark blue leggings, and yellow trainers. Her left wrist bears the Yo-kai Watch Model U prototype, later enhanced to Model U2. Fascinated by science fiction, outer space, and anime merchandise, Hailey habitually connects daily occurrences to her beloved show "Sailor Cuties," occasionally vexing her Yo-kai partner. She eagerly pursues mysteries and adventures yet expresses disappointment when events lack extraterrestrial links. Self-identifying as an "all-around nerd," she sporadically reveals insecurity through hallucinations of her giant head in rare dialogue sequences. After missing a desired figurine at an anime store, she acquires the Yo-kai Watch Model U prototype and encounters the Yo-kai Usapyon in an alley, forging a partnership. They co-found the Ha-pyon Detective Agency (player-customizable name) to investigate Sparkopolis' Yo-kai mysteries, collaborating on a rocket to realize Usapyon's former owner Dr. Hughly's ambitions. In Yo-kai Watch 3, she allies with Nate Adams to counter the Ghoulfather in Chapter 6 and joins Buck to probe Hazeltine Mansion in Chapter 7. Within Yo-kai Watch 4, she detects anomalies of future Yo-kai appearing in the present timeline. Kidnapped by the Yo-kai Fukurou under the mistaken belief she is a princess, she is rescued by Nate, Summer, Cole, and Bruno. Post-rescue, she aids quests enabling players to befriend Usapyon and appears with him across multiple locations. In Blasters++ mode, she becomes playable via possession mechanics using Yo-kai Drones for combat. Her anime debut occurs in "Usapyon Is Here!" with recurring roles in Season 3. Notable arcs include racing Nate in the Yo-kai Grand Prix, reconciling with Usapyon in episode 134, and competing for the Space Wars X Sailor Cuties Box in episode 149. Films depict her in varied attire: a Santa costume during Christmas deliveries, winter wear during interdimensional travel, and Hawaiian outfits in final scenes. Her relationships encompass a rivalry with Nate despite teamwork, a steady friendship with Jessica despite differing interests, and caring for her bothersome younger brother Joshua. Her detective partnership with Usapyon persists despite his frequent irritation at her cosmic analogies. The name "Hailey Anne" subtly evokes "alien," with "Hailey" possibly alluding to Halley's Comet. Early localization drafts used "Gracie" as a placeholder name and "Sailor Star" for her favorite show, while her Japanese catchphrase "Chiwatchi!" mirrors Ultraman's Spacium Ray pose.