Rinji

was a shinobi who appeared in the second Naruto Shippūden filler arc and was an underling of Orochimaru.

Personality
Rinji had a laid back attitude and was rarely worked up about anything. At the same time, he was shown to have sharp intellect and was a planning type.

Abilities
Rinji was a Bat-user; he had the ability to use ultrasonic waves using the Bat Controlling: Ultrasonic Waves so that he could communicate with Bats as he could control them, allowing him to survey the surroundings and give battle instructions to his subordinates. He also appeared to have a sonar-like power of his own that allows him to detect sound from a large radius.

Three-Tails Arc
After the selection battle Kabuto Yakushi and Guren held in the hideout, Rinji became Guren's subordinate. When Guren returned, she orders him and the rest of his team to dispose of Team 8. During which the fight he took on the role of leader and presumably used his sonar powers to allow his team to fight in Kigiri's Smokescreen Technique. After feeling that he analyzed his opponent's skills enough, he was ready to finish them, until he detected Shino Aburame's insect coming. Feeling the increased danger, he ordered his men to retreat.

Later, Rinji and the rest of the team came to Guren's aid when her crystal barrier was destroyed by Team 7. After retreating, the team, minus Gozu, was ordered to stop Team 8 from pursuing them. Rinji used his bats to try and catch the Konoha ninja by surprise, but Hinata Hyūga's Byakugan nullified his efforts. The battle was interrupted by the actions of the Three-Tailed Giant Turtle and Rinji and his team had no choice but to fall back again.

After meeting up with Kabuto again, it was then revealed that Rinji was a spy for Orochimaru who was ordered to keep an eye on Guren. It was also revealed that he had spent years acting as spy, inserting himself into villages and even as a fellow prisoner in Orochimaru's dungeon. When talking to Gozu, he claimed his actions were to aid his sickly sister from a far off village. When they were once again sent to stop Team 8, Rinji did not participate, allowing his team-mates to be defeated. Instead, he noticed the attempted sealing of the Three-Tails. When he was unable to stop it by himself he had Guren come help him and they ultimately proved successful. Rinji continued to show a number of uncharacteristic behavior after that, but this was later revealed to be Kabuto disguised as Rinji; Kabuto revealed that he killed the real Rinji. When Guren planned to run away with Yukimaru, Kabuto summoned the real Rinji using Dead Soul Technique, who fought with Guren. His bats' ultrasonic waves were shown to break Guren's Crystal Release, making the Crystal Release useless against Rinji. To protect Yūkimaru, Guren crystallized herself, along with Rinji, which caused them to fall into lake. Guren was able later saved by Gozu.

Trivia

 * Despite Rinji's troubled relation with Kabuto, they ironically shared one trait: they both had spent many years acting as spies and had a knack for appearing genuinely cheerful and kind-hearted to strangers to better deceive them.
 * Rinji may or may not possess the disappearing in flame technique, depending on whether or not Kabuto had replaced him by that point.