Birthdate: February 28, 1986 (1989 in the anime)
Zodiac sign: Pisces
Hair color: Brown
Eye color: Brown
Height: 179 cm (5'10")
Weight: 64.1 kg (141 lbs.)
Blood type: A
Occupation: high school student, a university student, detective
Age (during the series): 17-23
Likes: justice
Dislikes: evil

Light, born on February 28, 1986, is a third-year high school student (12th grade) at Daikoku Private Academy (大国学園, Daikoku Gakuen) who also attends supplemental classes at Gamou Prep Academy at the beginning of the story. Light has a father, Soichiro Yagami, who is the head of the Police Force. Light also has a mother, Sachiko Yagami, and a younger sister, Sayu Yagami.

In Spring 2004, Light becomes a first-year student (freshman) at To-Oh University (東応大学, Tōō Daigaku), becoming one of two freshman representatives; L is the other freshman representative. During a tennis game with L at To-Oh, spectators reveal that Light was the junior high school tennis champion in 1999 and 2000. After his 2000 victory, Light quit tennis as he entered high school.

Yagami Light is a brilliant college student. Nicknamed "Kira," he uses the Death Note to create his ideal world of justice under him; its new God. Though he looks frail, Light is an extremely athletic person, with an aptitude to find an opponent's weak point. He is a genius, which adds to his notion that only he is fit to judge humanity and steer it on a proper moral course.

He gets shot by Matsuda after his plan failed and then dies because Ryuk wrote his name in his Death Note. (January 28, 2010, in the manga; January 28, 2013, in the anime)