Beads of Subjugation

The Kotodama no Nenju (言魂の念珠, lit., "language power rosary"), called the Beads of Subjugation in English, is the title of the rosary/necklace that Inuyasha wears around his neck. When activated by the use of a particular word, the beads glow and bring the wearer under control (in a manner of speaking). In Inuyasha's case, it's usually referred to as the sit! command.

Purpose and History
Originally, it was Kikyo who was going to put the beads on Inuyasha in order to make sure he behaved. She told Kaede that she was going to trick him into wearing them by telling him they were a gift. She admitted it was a bit underhanded, but by this point, she had already decided she wasn't going kill him, but knew he might still cause some mischief. She ultimately decided against it when he gifted her with one of his late mother's treasures: a shell of lipstick.

Fifty years later, a desperate Kagome released Inuyasha from his seal so he could kill Mistress Centipede. Not three seconds after dispatching the demon, he turned on Kagome, intent on taking the Shikon no Tama for himself. She fled and he gave chase, prepared to do whatever he had to to get it, even kill. During the pursuit, Kaede uttered a chant and the beads found their way around Inuyasha's neck. She then told Kagome to "say the word". Thinking of his dog ears, Kagome says "osuwari" (お座り), meaning "sit (to a dog)". The beads shined and brought Inuyasha slamming to ground. (He was actually standing on a bridge at that moment, so he slammed straight down through the wood and into the water below.) This becomes a running gag through the entire series.

In InuYasha the Movie: Swords of an Honorable Ruler, a super, super charged "osuwari" caused the Kotodama no Nenju to more or less explode. Inuyasha spent the rest of the film without them, and a worried Kagome found herself wondering if she still had a connection to him even though he was without them. A scene following the credits showed Kagome tricking Inuyasha into wearing the beads again in very much the same manner Kikyo had planned to do. He continued to wear them for the rest of the series.

Attributes

 * Once they are placed on the demon or hanyo target, the Kotodama no Nenju can only be removed by the "word sayer". Try as they might, the wearer cannot remove, break or cut the beads from around their necks.
 * Only one person can activate the beads. Others have tried and failed, and Kaede, the one who put the beads on Inuyasha in the first place, has been shown asking Kagome to make him sit on her behalf.
 * Activating the beads causes the wearer to fall at a high speeds and land agroof.
 * Even if the wearer is already agroof, the repeating of the trigger word pulls them further still into the ground and continues to cause pain.
 * As a spiritual artifact, the Kotodama no Nenju can have an effect on demonic energies within the immediate vicinity.
 * When Tessaiga was broken and Inuyasha kept reverting to his demon form, Kagome used the beads to not only knock him unconscious, but also to temporarily force his demon blood back into remission.
 * In Swords of an Honorable Ruler, the spiritual power from the activated beads is enough to drive off the demon sword Sounga, breaking its hold over Inuyasha and sending it rocketing away at high velocity.
 * Also in Swords of an Honorable Ruler, Rin threw a couple of the beads at a demon that was holding Kagome. The spiritual essence of two beads that hit its face was enough to melt its entire head into a sizzling nothing.