"Hatena Illusion" centers around Makoto Shiranui, a young aspiring magician who dreams of following in the footsteps of his grandfather, a legendary stage magician. After his grandfather's passing, Makoto moves to Tokyo to live with his childhood friend, Kana Hoshisato, and her family. Kana, a cheerful and supportive girl, shares Makoto's passion for magic and often assists him in his performances. The story takes a fantastical turn when Makoto encounters a mysterious girl named Mena, who claims to be a magical being from another world. Mena possesses the ability to manipulate illusions, a power tied to a magical artifact known as the "Hatena."

As Makoto and Kana become involved with Mena, they uncover a hidden world of magic and intrigue. Mena is pursued by a shadowy organization seeking to exploit her powers and the Hatena for their own nefarious purposes. The trio embarks on a journey to protect Mena and uncover the truth behind the Hatena, which is said to grant immense power to its wielder. Along the way, they face various adversaries, including other magical beings and humans with their own agendas. The narrative explores themes of friendship, trust, and the pursuit of dreams, as Makoto and Kana strive to balance their ordinary lives with the extraordinary challenges they face.

The characters are defined by their relationships and growth throughout the story. Makoto is determined and resourceful, driven by his desire to honor his grandfather's legacy while protecting those he cares about. Kana serves as both a grounding force and a source of emotional support, her unwavering loyalty and optimism complementing Makoto's more serious demeanor. Mena, initially enigmatic and reserved, gradually opens up to her companions, revealing a vulnerable side beneath her magical abilities. The dynamic between the three characters forms the emotional core of the series, as they navigate the complexities of their shared journey.

The plot unfolds through a mix of action, mystery, and lighthearted moments, blending magical battles with slice-of-life elements. The story delves into the origins of the Hatena and its connection to Mena, gradually unraveling the secrets of the magical world and its impact on the human realm. As the stakes escalate, the characters are forced to confront their own limitations and make difficult choices, testing their resolve and deepening their bonds. The series balances its fantastical elements with relatable character-driven storytelling, creating a narrative that is both engaging and emotionally resonant.