|Height||5'4 (160 cm)|
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 seemed to be a cheerful and sociable person, as she was often seen with many female classmates. She was apparently good friends with Yumi Ogura and Sachiko Nakajima as she was seen with them most often. Despite the tragedies that have befallen her and her classmates, she mostly maintained 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 travels to Sakitani along with the rest of the class. There, she shared a room with Sayuri as Yumi was depressed after the deaths of Aya and Atsushi and chose to be alone. During dinner, she shared a table with countermeasures team due to her association with Yumi.
In "Makeup", after she heard Takako's broadcast, she and Sayuri 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 serious 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, along with Sayuri, Yukito, San and Noboru who had also gotten out of the lodge.
- In class, she sits in the column of seats by the window, the fourth row from the front, behind Yumi Ogura. To her right is seated Takeru Mizuno, and Kazue Satou 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.
- Main article: Matsuko Arita/Image Gallery