|Full Name||Autonomously Thinking Fixed Artillery|
|Date of Birth||January 1|
|Species||Artificial Intelligent Unit|
Autonomously Thinking Fixed Artillery (Japanese: 自律思考固定砲台 Jiritsu shikō kotei hōdai), more commonly known as Ritsu (Japanese: 律 Ritsu), is a major protagonist of the Japanese manga and anime series Assassination Classroom. She is a Norwegian artificial intelligence unit sent to kill Korosensei, and as such is a "student" of Class 3-E. She is the first of two transfer students to join Class 3-E, succeeding Itona Horibe, though the two were supposed to begin attending classes together.
Saki Fujita voices Ritsu in the original Japanese anime, while Bryn Apprill in the English dub.
Ritsu's exterior appearance is a large black brick of 170cm (5'7") height. Originally, she has a small screen showing just an emotionless head, though this screen was later enlarged by Korosensei, giving her a full-body appearance.
Ritsu has large blue eyes with large eyelashes, though her eyes were red before she was remodelled. She has blonde (pink in the anime) hair with a white, metallic hairband. She is commonly seen wearing Kunugigaoka Junior High's winter uniform, though she often changes her appearance to match whatever her classmates are wearing.
Prior to being remodelled by Korosensei, Ritsu was an emotionless being, focused entirely on killing her teacher. She had no concern for her classmates, and was willing to injure them if it could get her closer to her goal. After her remodelling, however, she prioritizes cooperation with her classmates, and is quite cheery to others. She is always honest and nice to those she works with, and has somewhat of her own volition.
- Unsurprisingly, Ritsu is the heaviest student in Class 3-E, weighing 499kg (1100 lbs).
- As an artificial intelligence unit, Ritsu is not allowed to take school-wide tests such as exams. As such, she has a stand-in take her place. This stand-in is the daughter of Karasuma's immediate supervisor. Ritsu herself acts as a tutor to this stand-in.