She has brown, straight, shoulder length hair and brown eyes. She is usually seen wearing the standard school female uniform. Apparently, she wears a yellow camisole and blue shorts underneath her uniform, as can be seen on the school trip when she was escaping the burning inn.
Matsuko seems to be a cheerful and sociable person, as she is often seen with many female classmates. Despite the tragedies that have befallen her and her classmates, she maintains her sanguine nature, unlike Naoya.
She made her debut in "Rough Sketch", as a background character in class 3-3. She was also present when Mr. Kubodera committed suicide in "Sphere Joint". She and the other students watched in horror as the teacher repeatedly stabbed himself in the neck.
In "Glass eye" she is seated at the same supper table as Yumi Ogura, Takako Sugiura and Izumi Akazawa. In "Makeup", after she heard Takako's broadcast, she and Sayuri, her roommate, left their room to see what the commotion was about. She was present when the others confronted Kouichi after they heard that Mei was the dead one.
In the chaos that followed ("Stand By Oneself"), Matsuko, having become separated from Sayuri, was left wandering the mansion looking for a way out. Entering one of the rooms, she was caught in an explosion and hurled through a window. Miraculously, Matsuko survived this without injuries, though she was a bit worse for wear. Matsuko eventually found her way to Chibiki's car, where she saw Chibiki, Yuuya, and Naoya who escaped the inn coming towards her. She answers when Chibiki questioned that no one else made it yet that she was the only one there. She then helps in looking over the injured Naoya with Yuuya. Later on, she is seen at the car with Sayuri, along with Manabu, San and Yukito, who had gotten out of the lodge.
Main article: Matsuko Arita/Image Gallery
- She sits in the class in the column of seats by the window, fourth row from the front, behind Yumi Ogura. To her right is seated Takeru Mizuno, and Kazue Etou sits behind her.
- Her first name, Matsuko, means " pine tree child ".
- Her home address is 3-11 Asamida Yomiyama City
- She is ranked A in Another characters ranking.