Kunai can also be stored on the arm with the user's spring wire, as seen in Naruto Uzumaki when fighting with Sai when they first met. They can be used for close combat, like normal knives. source
watch: HACKER CAUGHT ON CAMERA –~– Using Naruto gadgets I become a fruit ninja in real life! ▶ Use code chadwc for 10% Off at ▶ Chad Wild Clay Marathon – You guys suggested Naruto the Japanese Manga series as the next ninja gadgets. So now I test them out...