Akahoshi

"Third Hoshikage: This is madness, Akahoshi. You've lost your mind. Akahoshi: It's you who lost your mind, you old fool. Now go and sleep with your ancestors. Your journey is at an end. Leave it to the next generation to give this village the power to rival the five great hidden villages! Hehehahaha!!"

- Akahoshi assassinating the Third Hoshikage in Naruto episode 181.

Akahoshi is the main antagonist of the Star Guard Mission Arc. He assassinated the Third Hoshikage with the help of his allies, Shiso and Yotaka when the Third discontinued to star chakra training. After the Third's death, Akahoshi manipulated the people in the village into doing the star chakra training despite knowing its danger. He wanted to gain the full power of the Star chakra to one day dominate all Five Great Nations.

Personality
Akahoshi was obsessed with obtaining power and followed strictly behind the ideology of individuals dying for the greater cause of the village. His ideology and stubbornness, led Akahoshi to depravity. In the quest to obtaining more power for the village, Akahoshi murdered the Third Hoshikage because the latter outlawed the practice of using star chakra. Akahoshi did not care about the dangers the star chakra posed to the children of the village and encouraged them to continuously train in hopes of building up a strong military force in the village.

Aside from his calm and commanding personality he displayed, Akahoshi revealed his true nature as sadistic individual who laughed after murdering the Third Hoshikage and as a stubborn person who wanted power over the safety and lives of the villagers. With his henchmen, Shiso and Yotaka, Akahoshi only cared for them because of how helpful they were to him but did not cared about their safety when he recklessly used the star chakra. Akahoshi also displayed selfishness and brutality by how he went on a rampage when he gained the full power of the star chakra not caring about the safety of his fellow villagers.

History
Under the Third Hoshikage's rule, Akahoshi served as a ninja under his rule. When he learned about Natsuhi and Hotarubi and how they were against the star training because of its dangerous effects, the Third Hoshikage ended the star chakra training but banished them. Akahoshi disagreed with the Third Hoshikage's decision to end the star chakra ending over the safety issues involved. One night, Akahoshi and his men Yotaka and Shiso assassinated the Third Hoshikage. They managed to cover up the assassination leading the people in the village to think that the Third died of other causes. When Akahoshi came to power after the Third's death, Akahoshi resumed the star training. Concerned about the meteor not getting stolen, he hired leaf ninjas (Neji Hyūga, Rock Lee, Tenten, and Naruto Uzumaki) to protect the star.

When he learns about Natsuhi's motives, he disguises himself and captures Sumaru (Natsuhi's son). At the time he did this, he encounters Naruto and Neji who attempts to stop him. He brings Sumaru back to his building in hopes of luring out Natsuhi. Akahoshi manages to encounter Natsuhi and wants her to comply with his demands for her son's safety. Naruto and Neji manages to make it to the destination where Akahoshi and Natsuhi were at. When they continue their fight, Akahoshi attacks Natsuhi with his star chakra attack which results in her and Naruto falling off the cliff they were at. Neji asks why he attacked Naruto to which Akahoshi lies that he was in the way.

Akahoshi soon learns that Sumaru was taken by Rock Lee and Tenten. Akahoshi later encounters Natsuhi again and confesses to murdering the Third Hoshikage. He fights Natsuhi until he defeats her. Later when Akahoshi was telling the village about his plans as the Fourth Hoshikage, Akahishi encounters Natsuhi and the leaf ninjas again. Akahoshi uses his star chakra to take control of Sumaru's mind for a moment to force him to say that he will sacrifice himself for the village. Akahoshi forces Natsuhi into a situation where she has to choose to either save her son at the cost of her life or die. Akahoshi murders Natsuhi, tells the leaf ninja that their job in his village is done, and leaves Sumaru to the leaf ninjas calling him the son of a traitor.

In the village, Akahoshi is confronted by people in the village over the effects of the star chakra training on the children. When they press him for his actions, Akahoshi stubbornly supports the star chakra training and did not care what happens to the children because he sees them as necessary sacrifices to the village's growth. After getting press more by the villagers, Akahoshi confess to murdering the Third Hoshikage with the help of Yotaka and Shiso. Shiso questions whether Akahoshi takes things too far. Out of desperation, Akahoshi responds by implanting the meteor into his chest and gain more power. With his new power, Akahoshi attacks everyone indiscriminately. Naruto uses his rasengan to destroy the meteorite which results in Akahoshi's defeat. Afterwards, Akahoshi, Yotaka, and Shiso are arrested by the authorities in the village and imprisoned.