Sanae is a middle schooler who skips a grade to attend the same high school as Rikka Takanashi, whom she reveres as her master. Sharing a strong affinity for delusional fantasy, Sanae joins Rikka’s self-created club, the Far Eastern Magic Napping Society of Summer, where she expresses her “magical powers” as the wielder of Mjolnir Hammer, her imaginary weapon embodied by her long twintails.

Despite her eccentric outward behavior, Sanae comes from a privileged and intellectual background. She is academically gifted, scoring highly in tests and often surprising others with her intelligence. Her delusions act as a protective barrier from the responsibilities and pressures of the real world.

Sanae is a petite girl with long blonde hair tied into high, thick twin drills that she uses as mock weapons during her fantasy battles. She has bright blue eyes and wears the standard high school uniform, though she often modifies it slightly to suit her chūnibyō flair.

Her overall appearance gives off the impression of an energetic, slightly spoiled girl with an affinity for the dramatic and whimsical. She is often seen making exaggerated poses or movements when acting out her delusions.

Sanae is enthusiastic, hyperactive, and deeply committed to her delusions. She uses grandiose language, often referring to herself as a wielder of supernatural powers, and engages in pretend battles with fellow chūnibyōs or her “rival,” Shinka Nibutani (whom she stubbornly calls “Mori Summer”).

Beneath her eccentric personality, Sanae is loyal, compassionate, and emotionally sensitive. Her chūnibyō behavior is not just for fun it is a form of emotional expression and escapism. She struggles with feelings of loneliness and attachment, particularly toward Rikka and Shinka, and has difficulty expressing those emotions in a grounded way.