Hyde Kido (Unknown Actor), is the main character of Under Night In-Birth and its updates. He returns in BlazBlue Cross Tag Battle as a playable character and as one of the four main protagonists.
A normal high school student living alone, he was drawn into the Hollow Night, a phenomenon which saw him nearly killed by invisible beings called Voids. He was saved thanks to the timely intervention of Linne, a nearly-century old being in the body of a young girl whom he saved from a common thug back in a daylight, and her ally, the giant Waldstein. The event caused Hyde to awaken to becoming an In-Birth, allowing him to harness the powers of EXS, the source of all things. Grateful, he has since dedicated himself to helping her cause and ending the Hollow Nights for good.
Hyde's EXS Ability, the EXS of Jet Black "Void Red", allows him to summon a mystical weapon called the Indulgence of Rending, or the Insulator. With it, he can destroy the EXS of others, which allows him to kill Immortals and other such beings.