Kuroko 1 was infected with the Najin by Lieutenant colonel Kato in order to protect his legacy. He ordered the removal of Jang Tae-sang's Najin, leading him to lose his memory and continue his life as a civilian called Jang Ho-jae. Kuroko 1 is a cold, efficient man who puts the interest of Yeonseung Biotech before all. He possesses all the abilities provided by the Najin: strength, resistance and high speed. Also fights with a katana. Works with Maeda and takes unwilling care of Seung-jo.