Verified answer

I'm horrible at explaining, i would probably just confuse you, so this is from wiki =]

180

It is revealed that the masked ninja who stole the star is Sumaru's mother, and that Akahoshi is the one who kidnapped Sumaru. The group learns that the star training is potentially fatal to the ninja who take part in it, but resolve to find the star. Neji and Lee infiltrate Akahoshi's residence and rescue Sumaru. Meanwhile, Akahoshi approaches Natsuhi and demands the star in exchange for Sumaru, and the two fight. While Natsuhi gains the upper hand, Naruto and Lee intervene for Akahoshi, and Naruto manages to get close enough to punch Natsuhi. After he does, Akahoshi launches an attack at the two of them, dropping them into the Valley of Death.

181

Akahoshi says that the mission for the Konoha shinobi is over, but Neji says that as the star has not been recovered, the mission will go on. Neji, Lee and Tenten reveal the truth about Akahoshi to the trainees. Naruto awakens and hears about Natsuhi and her husband seeing the horrors of the star training, and trying to steal the star. After they were caught, the Third Hoshikage agreed to end the star training if they left the village and watched from afar to prevent it from resuming. Natsuhi and her husband accepted, asking the Hoshikage to tell Sumaru that they had died. Akahoshi tracks down the star, and reveals that he assassinated the Hoshikage in order to resume the star training. He fights Natsuhi and absorbs his subordinates' chakra to grow stronger, but Naruto's teammates and the star trainees arrive.

182

As Sumaru, the rest of the Star trainees and Naruto's teammates arrive, Akahoshi takes Sumaru hostage and forces Natsuhi to hand over the star. Neji examines Natsuhi and reveals that she could die if she uses her star chakra jutsus again. After Sumaru awakens, he speaks with his mother, who reveals that while she knew that she had to leave him behind to spare him the pain of becoming an exile, she regrets leaving him. While Naruto and Lee insist on going after Akahoshi, Neji says the mission is over and they, as Leaf ninja, cannot betray a client. That night, Natsuhi goes to the star temple to steal the star, but is killed by Akahoshi and his men. Sumaru, following with the Leaf ninja, senses her death and flies to the temple. Akahoshi declares himself Fourth Hoshikage and orders his ninja to kill the Leaf ninja, Sumaru and Hokuto if they set foot in the village.

183

After Akahoshi tries to execute Sumaru, Hokuto and the rest of the children stand up to protect their village, revealing the poisoning caused by the star. After learning the truth, the adults turn on Akahoshi as well. After Akahoshi nearly kills Mizura, he is given no second chances. Not being one to lose, Akahoshi fuses his body with the Star, causing his chakra to go out of control. Naruto, guided by Natsuhi' s spirit, destroys the star and defeats Akahoshi. Although Tsunade initially seems upset over Naruto failing the mission, she concedes that the mission was "trash" due to being ordered by Akahoshi himself, and heals the children of their poisoning.