Teko lives with her elderly grandparents, the Tachibanas, while her parents work overseas. After the Tachibanas take in Lalabel, Teko becomes one of Lalabel's closest human friends. She attends school alongside Lalabel and their mutual companion Toko, forming a central trio. Sensitive and romantic by nature, Teko contrasts with Toko's athletic tomboyishness and Lalabel's magical origins.

Her family connections include an uncle who operates a hostel, visited during a summer vacation storyline. When her uncle and aunt depart to attend an acquaintance's operation, their son Ryota manages the hostel alone. Teko, Lalabel, and Toko assist Ryota with the hostel duties, showcasing Teko's family loyalty and sense of responsibility.

Within school life, Teko navigates a love triangle involving herself, Lalabel, and classmate Morio. All three develop feelings for Morio, though he remains romantically uninterested in any of them. This subplot explores Teko's emotional growth, which extends to discovering human traditions like birthday celebrations—first experienced during Granny Tachibana's community birthday.

Teko grounds Lalabel's exploration of human customs and emotions, joining her daily adventures and confrontations with the antagonist Biscus. Her involvement continues through the series' conclusion, witnessing the final resolution between Lalabel and Biscus that costs both their magical powers. Afterward, Teko remains alongside Lalabel and Toko as they forge ahead.