Gender: Female, Guest's younger sister Age: 15 years old (Middle school student) Appearance: She has blue-black hair reaching down to her waist, blue and turquoise gradient eyes, a cute face, and a very short stature (similar to an 8-year-old). Her hair is characterized by several cowlicks sticking out in various places. Traits: Shizuka has a stutter and selective mutism, which worsened due to her poor interpersonal skills. She is quiet, clumsy at speaking, and unable to talk to people directly. She used to communicate by carrying a book and pointing at sentences, but since Rentarou installed a text-to-speech app for her, she communicates using an electronic voice that reads sentences from the book. Shizuka loves the book 'Secret Love Story' immensely and carries volumes 1, 2, and 3 in her bag at all times. Even when laughing because she's tickled, she rarely speaks directly, instead using her phone to play an electronic voice saying 'Laughed out loud' while laughing silently. In reality, her own voice is cute and beautiful. Despite her quiet and gentle appearance, she also shows a rich, playful emotional side. She loves libraries and is a library committee member. Usual Attire: She wears a school uniform consisting of a white shirt, a light navy knit vest, and a black pleated skirt. She is currently dating Aijo Rentarou.