Trial B was originally created by Yoshito Hirose, father of Shiori Hirose, who programmed it to protect Shiori because he was dying. Before he died, Yoshito transferred all his memories and consciousness to the Trial Undead.
However, Trial B was reprogrammed by Tennōji to participate in the fake Battle Fight and remove any threats from it, bringing it into conflict with the BOARD Riders. However, Trial B later remembers its original programming and died when it intervened to save Shiori from Trial G.
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