Secret of the Ninja (Choose Your Own Adventure #16) by Jay Leibold - Paperback

Choose Your Own Adventure: Secret Of The Ninja is an interactive gamebook in which YOU decide what happens next when a number of mysterious happenings take place around an aikido dojo in Kyoto, Japan. Readers aged 9-12 and beyond will use their ninja skills to investigate the appearance of a strange relic...and fight five ninjas at once! 

An ancient samurai sword arrives on the doorstep of your aikido dojo. Does the ninja sword hold magical powers that date back many decades ago? If you trace the history of this mystical sword, will your life be in danger? Without warning, five ninjas attack! Are they after the samurai sword, or out for your head?