Yuji Kaido is the main protagonist of Blue Gender. Diagnosed with an incurable disease (later discovered to be B-Cells), he is cryogenically frozen in 2009, with the hopes that effective treatment would be developed in the near future.


Not much is known about Yuji prior to his stasis. In 2009 he worked at a gas station in town and hung out with his best friend Takashi. Yuji was later diagnosed with an incurable disease that baffled doctors. As they had no idea how to treat it, Yuji was given the opportunity to become cryogenically frozen until a time where a cure could be found. Yuji accepted the offer, believing that he would only be frozen for a few years and that he and Takashi could then travel the world together.


In the year 2031, Yuji is awoken by a group of unknown soldiers who are frantically pulling his status tube away from an unseen danger. He is greatly confused at this, wondering what is happening and why he is there. All of a sudden, they are then attacked by a large insect creature who throws Yuji's tube across the corridor