Ninjago: Discover 24 Ninjago Rewrite ideas on this Pinterest board 700+ Free Ninja Hattori & Ninja Images Pixabay Ninja tribute Ninja Assassin Costume (Black & Blue). This children's ninja assassin costume is perfect for any fancy dress party. It includes a black and blue top and trousers, as well as a hood and mask for a fully completed look. Simply add shoes and a weapon of choice for an authentic look. Features: Hood. Mask. Top. Trousers. Size: Small: Age 4 6 Years (Height 115 128cm). Medium: Age 7 9 Years (Height 130 143cm). Large: Age 10 12 Years (Height 145 158cm).