時は2022年、環境破壊の進む地球。未来への希望は炎や水など自然エネルギーを生み出す忍者に託された。そこで政府は忍者法を交付。全国民に忍術の修行が義務づけられ、世の中は忍者社会となった。だが、それらすべては闇の忍者軍団・虹蛇の陰謀であった・・・世界を掌握しようと暗躍する虹蛇に敢然と立ち上がったのは伝説の忍者、仮面ライダーシノビである！
As the episode opens Rentaro faces off against his sister Iroha in a ninja match, but he proves to be unable to beat her as his fire ninpo is too weak and she simply reflects a stronger version of it back at him and pinning him down with shurikens, defeating him which ends the match and earning her 10 points. The forest they were battling in was a holographic simulation which dissolves and the spectators cheer for Iroha's victory and advancement in the 5th Annual Ninjutsu Championship Tournament.
