|Base of Operations||Kunugigaoka Junior High School: Class 3-E's mountaintop classroom|
|Manga Debut||Chapter 1|
|Japanese Voice||Nao Tōyama|
Nagisa Shiota (潮田 渚, Shiota Nagisa) is a student of Kunugigaoka Junior High School. He is assigned to Class 3-E, where he trains to become a professional assassin, with his teacher as the target. He is the deuteragonist of the Assassination Classroom series.
Nagisa Shiota is a young boy, with unkempt, light-blue hair. His hair is divided down the middle, and layers of hair jut out from either side. He has eyes of corresponding color. His school uniform consists of a long-sleeved, collared white shirt, along with a black vest worn over it, a black tie, and a pair of plain trousers.
Nagisa is a calm and collected individual. He is exceptionally observant and circumspect of his surroundings and the situations that develop around him. He tends to pay strict attention to Korosensei, in hopes to understand the motives of this mysterious being. He compiles the information he has gathered in his notes for reference.
Nagisa is generally very friendly and amicable around others, and he enjoys spending time with his classmates and learning about them. He greatly respects Korosensei, and sees him as an extremely reliable teacher. As assessed by Tadaomi Karasuma, Nagisa has a natural talent for assassination; he has the capability of drawing closer to his opponent while concealing his bloodlust, making his opponent falter through bloodlust alone, and being at ease—namely, "acting in front of an audience." A snake symbolizes his covert yet potent bloodlust, as well as his stealth.
When Nagisa was assigned for Class 3-E, the classmates deemed him as inferior and refused to keep contact with him. His previous homeroom teacher condemned Nagisa, for the higher-ups had lowered their evaluation of him as an instructor, and stated that the only good thing that came about this was Nagisa would disappear from his sight.
At the start of his third year in junior high, seventy percent of the moon mysteriously disappeared in an explosion. Then, Korosensei arrived with the government authorities to Class 3-E. Korosensei announced that he will be their homeroom teacher, and Tadaomi Karasuma assigned Nagisa and his classmates the mission to assassinate Korosensei, or the world will be destroyed in a year. After he relayed the necessary details, he offered them 10 billion yen as compensation for the completion of the mission, and provided them with special weapons. Korosensei, who was unconcerned about the strategy to kill him, urged the students to spend the "final" year with him in a meaningful fashion.