Soundproof Tag

Soundproof Tags (防音札, Bouon Fuda) are scraps of paper inscribed with a special writing, centering around the kanji for "soundproofing" (防音, bouon). Infused with chakra, they are used by Yasu to silence things. When placed on an object or person, any sound they make is dampened.

Yasu uses this in conjunction with his kekkei genkai, Concealment Release. Since his soundproof technique can only work on a few people at once, and cannot completely silence extremely loud sounds, these tags can help him. By placing a tag on someone, Yasu doesn't need to use his jutsu on them. They can make as much noise as they want and still not be heard. For noises that he cannot normally dampen very well, he uses multiple tags. He also uses them when he needs something to stay quiet until after he leaves, allowing him to focus on other tasks. Once he is long gone, the tag deactivates and the noise comes back.

Utilized Techniques
Concealment Release: Soundproof

Reference

 * Image used an explosive tag as a base.