Shuriken, the use of which was taught at dojo (halls used for martial arts training) as a 'martial art,' and the shuriken which ninja carried following its original use, should be treated as separate things.
「武術」としての道場などで教える手裏剣と、忍者が本来の使用意図で携帯した手裏剣は別物として考える必要がある。