"Ninja Gaiden" was Masato Kato's first full-time project as a video game designer, and he contributed the game's graphics, animations and instruction manual illustrations.Drawing inspiration from the "Mario" series, Yoshizawa kept the same title but changed everything else; it became a platform game as opposed to a beat 'em up such as "Double Dragon"; the gameplay was modeled after Konami's "Castlevania", with Ryu being equipped with a katana-like Dragon Sword, shurikens, and ninpo techniques such as fire wheels.