Ultraman Hikari is the secondary Ultra Hero of Ultraman Mebius. He was once an excellent scientist who was the chief of the Space Science Technology Bureau of the Land of Light. At one point, Hikari became Hunter Knight Tsurugi after his failed defense of the Planet Arb.

A long time ago, Hikari was the chief scientist in the Land of Light's Space Science Technology Bureau, known for multiple researches and inventions. His greatest research is the method to preserve and revive life forces, which earn him a set of Star Marks on his chest. At some point, he took in Ultraman Tregear under his employment and supervised his creation of the then-unnamed Taiga Spark. Although being used beneficially by his people, his research also ignited a war between alien races and was misused by invaders for their malicious means. Seeing the horrifying results of his actions, Hikari resigned from the Space Science Technology Bureau and embarked on a journey to study space.