Hikari Yagami

Hikari Yagami (夜神光, Yagami Hikari, reading unverified) is the child of Light Yagami introduced in Death Note: Light Up the NEW World. Conceived in secrecy, the child was intended to take over the mantle of Kira after Light's death.

Character
Very little is known about Hikari and very few people even knew of his existence. It is known from Ryuk however that the boy was easily corrupted by the power of the Death Note and became mentally unstable. This caused Hikari to become a merciless killer despite his young age. It is also known that he was not on good terms with his foster father, Teru Mikami, and was eventually betrayed and killed by Mikami.

Plot
At the film's climax, Yuki Shien reveals that Light fathered a son before his death in case anything were to happen to him. Named Hikari, he was first raised in the United States before Mikami was appointed the child's guardian. Some time after Light's death, Hikari was brought back to Japan by Mikami and entrusted with a notebook by Ryuk. After becoming insane from using the notebook, Hikari is killed by Mikami, who takes the notebook for himself. Shortly after, Tsukuru Mishima, who witnessed Mikami killing Hikari, shoots Mikami to death.

Trivia

 * Hikari's name is only seen written in the Death Note by Mikami, with the characters "神光" seen on the page.
 * Hikari's name is never spoken in the film, so the exact pronunciation is unknown. Hikari's name, written 光, means "light" in Japanese and is usually read as hikari. Other possibly pronunciations include Kaizechuu, Koukun, Koushou, Kouji, Kousou, Teru, Hiroshi, Mitsushi, Mitsuji, Mitsutsugu, and Mitsumune.
 * Hikari's mother is never revealed in the film.