Hunter Knight Tsurugi is a major character in Ultraman Mebius, originally appearing as a mysterious, powerful warrior associated with the Ultraman universe. He is the human form and later identity of Ultraman Hikari, a former scientist and fighter who was transformed by tragedy and revenge. In the series, Tsurugi serves as both an ally and a key figure in the larger conflict, guiding and supporting Mebius while revealing important connections to past events and the history of the Ultra warriors.