Genbu

The turtle's back has gathered so much plant growth over the ages that it reads as a genuine island. The Great Toad Sage once called it a paradise, yet for people it is nothing of the sort, strewn with the marks of death and combat and roamed by huge, savage beasts. The Falls of Truth lie somewhere on its surface. A Giant Squid once guarded the approach, attacking anything that neared, and a powerful barrier concealed it further, while the turtle's ability to swim off made it nearly impossible to locate without scouting from the air.

Genbu ranks among the largest beings in the whole series, if not the single largest, dwarfing the nine tailed beasts and the enormous summons of the Sannin and standing comparable to the Ten-Tails. Its hide is mostly grey, spikes jut from the shell, and its belly is blue. That shell is remarkably tough, shrugging off formidable techniques and able to shelter tailed beasts, and although the underside is said to be more vulnerable, it still endured one of Deidara's explosions without harm.

For all its overwhelming bulk, Genbu is said to carry itself with genuine humility.

A, the Fourth Raikage, and Killer B both trained on the island in their youth, and B grew close enough to the local wildlife to tame every animal there, later keeping a vacation home on the shell. With the Fourth Shinobi World War looming, the Shinobi Alliance chose the island as a hiding place for B and Naruto Uzumaki, the last two surviving jinchuriki, to keep them beyond Akatsuki's reach. A handful of Konoha ninja, among them Might Guy, Aoba Yamashiro, and Yamato, came along as guards with Motoi acting as their guide, and the official excuse for Naruto's presence was that he was studying the island's ecology.

Kisame Hoshigaki had slipped onto the island hidden inside the Samehada that B had taken from him, and once Naruto uncovered him he clashed with Might Guy before taking his own life, though his messenger shark still smuggled a scroll of intelligence out to Tobi and forced the turtle to relocate. Later, as Naruto pretended to survey the giant animals, Manda II clamped onto the creature's tail, drawing a cry that betrayed its position to Kabuto Yakushi and pinning it in place. Kabuto had the reincarnated Deidara plant a massive clay bomb that flipped the turtle onto its back, and a group of enemies landed on the exposed underside to fight. When the clash ended with Yamato captured, Onoki carried the entire island through the air to Kumogakure. Naruto and B were then kept under Alliance guard while Naruto trained to master the Nine-Tails' chakra, until he learned of the war and, with B's help, broke through the barrier around the turtle to join the fighting.