Only Natsuhi and Hotorubi, the parents of Sumaru, managed to survive the training, and both died eventually. Even if a ninja survived the training, the side effects would eventually kill them.

The training was eventually forbidden by the Third Hoshikage, after he realized the deadly toll the training took on those doing it the Star's intense radiation of chakra was too much for some shinobi to handle, and thus their insides began to corrupt and their organs to weaken, eventually leading to internal bleeding or organ failure. When this technique is fully mastered, it gives the user almost unrivaled chakra control, to the point where they can solidify it as a shield or create wings for flight.

The technique used to harness this power is the Mysterious Peacock Method. The First Hoshikage was able to devise a training method to allow the ninja in the village to harness the power of the star, allowing the ninja to gain supernatural chakra levels. The meteorite itself is not that large, but it emits a chakra-enhancing radiation. The other villages do not recognize Hoshigakure as an equal, nor is there any ninja truly worthy of the title. Its leader is the Hoshikage (星影, Star Shadow), though the leader is a Kage in name only. Dialog from its inhabitants suggests that the village can't have been founded much sooner than Konoha was. No trees or plants could grow around the vicinity after it landed. Hoshigakure was formed sometime after a strange meteorite, which they call the 'star', struck its location 200 years earlier. It is located in the Land of Bears and one of the lesser-known Shinobi Villages in the Naruto Universe. Hoshigakure (星隠れの里, Hoshigakure no Sato Literally meaning 'Village Hidden Among Stars') was introduced during the Star Village filler arc.

Naruto as sumaru