The Reikai Tracking Stickers (トラッキング=ステッカー) are the fifth spirit detective tool of seven. They are used by Botan during the second part of the House of Four Dimensions. It is a modification of the tattoo stamp seals used to keep track of inmates in Spirit World. It changes colors based on the appliers condition, differentiating between normal, a small wound, and a serious injury. It can only be removed by the applier, and will fall off if the applier dies.
The Mejiru Seals, or Underworld Tracking Stickers as they're referred to in the manga, appear as small circular devices with a dark border and a blank space in the center, presumably to allow for easy labeling.
The stickers, once applied, change color based on the condition of the applier. The color blue indicates the person's condition is normal, with yellow and red indicating minor and major wounds respectively. It is also important to note that the stickers memorize the distinctive aura print of the person who applied it, and only the person with that "spiritual blueprint" can peel it off. If that person dies, the sticker will fall off to indicate their demise to the wearer.
During the Chapter Black saga, Botan suggests using this item to allow the Yusuke retrieval squad to keep tabs on each other's physical condition as they are forced to split up in their efforts to find the captured spirit detective.
She suggests using the stickers to allow Kurama , herself, and the others to keep tabs on the groups physical status as they will be out of contact once they enter the four distinct sets of dimensional stairs. Hiei is reluctant to wear the stickers because he feels they're unnecessary, although it is probable he only refused to save face with regard to his concern, or lack-thereof, for the others' fates. After being reminded that he was the first to lose his soul during Kaito's taboo trial, he is somewhat more complacent and allows the group to place their stickers on him.
Later, after it is revealed that one of their number is an imposter, Botan has the clever idea to see which of them is unable to remove the sticker with their name on it from the surface it was applied to. This turned out to be useless however, as Mitsunari's copy ability allowed him to mimic Kuwabara's aura print, in addition to his other attributes.
- ↑ Yu Yu Hakusho manga; Chapter 118