The real Kamishiro Tsurugi was killed along with his sister Miku by the Scorpio Worm. Moments before his death, Scorpio Worm chose to mimic him only for Tsurugi's personality to eclipse the Scorpio Worm's own, leading it to lose its memories of its Worm identity and instead believe that it was Tsurugi Kamishiro. His butler Jiiya was aware of this, but did not dispense the information in the hopes that the Tsurugi would live on as a Worm mimickry and the Scorpio Worm would never regain control. Tsurugi at some point encountered the Sasword Zecter and became Kamen Rider Sasword, being contracted by ZECT to kill Worms.
