Shadow Ninja Aku (影忍者悪 Kage Ninja Aku) are the shadow ninja themed foot soldiers of CORE. They Travel through the shadows until they are needed. They are equipped with special Katanas that can also act as a chain whip that is hidden with the blade. When a bunch of the use them use the growing technique together, they can fuse together to form a Giant Shogun Ninja Zen Aku (な将軍忍者禅悪 Kyodaina Shōgun Ninja Zen Aku) which are equiped with a giant sword.