Hollow Kunai (中空クナイ) are custom-made kunai used by Kotarō Shimura. They resemble the standard kunai in appearance, but there is a hollow space in the blade and handle; Kotarō has also stated that they are much lighter than normal kunai, but break easier. Their most common use was to hide an explosive tag inside the hollow spaces, then throwing them at an opponent, allowing for a surprise explosion. These weapons were created by Kyoka Shimura.