Black Egg 10

The Black Egg 10 (黒卵十, Kokuran Jū ) were a set of ten school-aged children, all of shinobi descent and most of which who came from long lines of proficient sensor nin, who were captured by a kunoichi by the name of Fujiwara Nanaho and imparted with a Cursed Seal.

Using confidential clan records, Fujwara Nanaho identified descendants of the Fujiwara far enough removed to have joined or grown up in separate clans or countries. Through these distant members, Nanaho tracked the family trees of their sworn Countries' sensor-nin and chose the most likely candidates for her "program"; these individuals later came to be known as the Black Egg 10 through both her study notes and through the mission reports of tracking teams. These candidates, all in their first three years of the academy, were spirited away and taken hostage in a covert base in the Land of Snow.

Nanaho branded the 10 with a reverse-engineered Curse Seal designed to expand the victim's chakra pathways and increase chakra sensitivity. However, in order to prevent herself from being detected, Nanaho had designed the seals with a closed loop of activation chakra that fed off the host's own reserves. The pattern she had used left the seals highly unstable, resulting in massive trauma to her subjects' chakra paths and a hypersensitive perception factor. The youngest of the 10 died immediately upon receiving the seal and another member followed shortly after, within ten minutes of people branded. Three more suffered severe cerebral trauma resulting in epilepsy.

All eight of the surviving 10 were bedridden for months after rescue, recovering from severe and debilitating overstimulation. Nanaho was charged with illegal experimentation, medical malpractice, and the Fujiwara's personal charge of "Inhumanity". The last of these charges resulted in her exile from the clan; Nanaho was stripped of all rights to her surname, branded on both cheeks, and had her chakra signature removed from the Clan wards. She was sent away from the compound and ostracized by any of her previous family members she came across.