Kuroma Tatsushiro

Kuroma is the antagonist of Naruto Shippūden: Ryujinki.

Appearance
He is a young man with gray hair and green markings on his face. Like Akari, his younger sister, he has red eyes and small horns on his head, signifying a connection with the five dragons that he releases upon the world. He has numerous tags on his robe that allow him to use elemental attacks, and a large scroll strapped to his back with a dragon's head on one end. The light green medallion on his belt matches the one Akari wears around her neck, and presumably furthers their connection to the dragons. He is the host of a dark dragon, although this dragon is never seen, as he was freed from it being sealed within him before he could release it.

Plot overview
Kuroma was first seen when the team from Konoha tracked him down to his base. He explained his motives, to release the dragon within himself to free Akari from their burden, and set up a barrier to prevent the team from entering. Once Narut returned with the elemental orbs of the five dragons, he broke down the five barriers which each corresponded to an element, and pressed the switches behind them to release the barrier guarding Kuroma.

When Naruto finally entered into battle with Kuroma, his efforts to defeat him proved somewhat fruitless, until, all of a sudden, Sasuke arrived, having just finished a battle with Kisame up above, who then disappeared. Having already perceived Kuroma as a threat to his plans to kill Itachi, Sasuke attacked him, but ignored Naruto. After Naruto was seemingly defeated, Sasuke left for unknown reasons, and Naruto's friends attacked Kuroma, only to be blown back by his power. Seeing his friends get hurt, Naruto went into a Three-Tailed State after seeing his friends get hurt. Akari plead with Naruto not to kill Kuroma after Naruto had defeated him, but Naruto, influenced by the Nine-Tailed Fox, simply charged at her instead. Just before he got to her, though, Sakura shouted his name, bringing him back to his senses. This, however, gave Kuroma enough time to initiate the unsealing ritual to release the dark dragon sealed within himself.

However, before he could actually release the dragon and transform into it, Akari pushed him out of the way, taking the unsealing for herself so that she wouldn't lose Kuroma. As Kuroma began to mourn the loss of Akari, she turned into a dragon of light. Akari then became the final boss of the game. She had six forms matching up to the elements of the previous five dragons, and Naruto had to eliminate each one before he could deal the finishing blow. Once defeated, Akari returned to normal, and she and Kuroma soon discovered that their horns, as well as Kuroma's facial markings, had disappeared, freeing them from their burden. The two departed together to lead new lives, no longer having to protect the Dragon Sword or the sealed dragons.

Trivia

 * "Kuroma" means "pure black." This is in contrast with Akari's name, which means "light."