The Checkmate Four's original King is referred to as the Dark Kiva, the lord of all Fangires and the original Kiva who was a threat to humanity in his time. Despite being married to the previous Queen of the Checkmate Four, Maya, he has no actual love for her as her purpose to him was the birth of his son, Taiga Nobori. Due to Wataru Kurenai's actions in 1986, the King loses the powers of Dark Kiva to Otoya Kurenai. Otoya would use this power to battle against him along side the time-traveling Wataru as Kiva Emperor Form, ultimately weakening the King enough that Taiga redirected his attack and destroyed him. The use of the Dark Kiva power would ultimately cost Otoya his life. Taiga Nobori was born prior to 1986 as the first born son of Maya, the Queen of the Checkmate Four, and the original King. He would receive the title of King at infancy after his father's death before he was spirited away by Maya to be raised by Mamoru Shima as a human child. He wears a glove over his hand to conceal his Checkmate Four crest. After learning of his true nature as the Fangire offspring of the previous King and Queen of the Checkmate Four, Taiga developed a disdain for humans as he intends to prevent the progress of humanity from moving forward to the point of becoming a problem for Fangires like with Ixa.
His meeting with Wataru and taking his title as the Fangire King, as well as his eventual downward spiral, forces Taiga to knock out Maya to take the power of Dark Kiva as his own and reclaim his birthright. He would use the Dark Kiva power to settle things with Wataru once and for all, but in the end, he relents and uses the power to fight the revived Bat Fangire. The Dark Kiva powers would stay with Taiga after the final battle was over. Dark Kiva only appears to have one form, similar to that of Kiva Emperor Form in black and red. However, Dark Kiva doesn't require the use of a being such as Tatsulot to achieve this form, and has no chains on his body as Kiva needs to control his power. As Dark Kiva, the King has access to an unlimited potential of power that is hindered within his successor such as telekinesis and the use of the Kiva insignia as a weapon. As Maya would later explain, the Kiva power cannot be used by a normal human, as usage would ultimately result in death. This would prove to be true, as Otoya had used the Dark Kiva power a total of three times before finally dying due to the strain it put on his body. Shima also mentioned this when Wataru revealed his heritage to him.