Tsukushiin Touko attends Third High School as a first-year Course 1 student, hailing from the ancient and honorable Tsukushiin Shinto magic lineage linked to the Shirakawa clan. Her family specializes in water-based magical practices. She possesses long blue hair reaching her thighs or hips, typically featuring a single ahoge, and vivid orange eyes. While usually in her school uniform, she dons traditional Shinto shrine maiden attire elsewhere due to her heritage. Touko speaks with archaic flair, using "washi" for herself, "yoi" instead of "ii," and "ja" for modern particles like "da." Her personality radiates cheerful confidence and positivity, motivating Third High teammates while displaying genuine enthusiasm toward rivals like Mitsui Honoka. Magically, she commands Shinto-type ancient magic, excelling in Water Spirit Magic to summon spirits for whirlpools, tidal waves, and tactical barriers. She seamlessly merges this with modern Movement Magic, applying both simultaneously without focus loss—describing spells as extensions of her body. Her heightened intuition allows near-accurate reading of unspoken thoughts. During the 2095 Nine Schools Competition, she placed second in the Women's Newcomers Battle Board event. Her strategy blended authentic magical traps with decoys to disrupt Honoka's light-based senses while using Movement Magic to control engagement distance. She employs twin bracelet CADs: a red device on her right arm for modern magic and a blue one on her left for ancient and Water Spirit Magic. She shares close bonds with fellow Third High students Isshiki Airi and Kanou Shiori, having trained intensively with them for the competition. Touko maintains respectful rivalries with opponents like Honoka, valuing challenging adversaries.