Rinji

is a shinobi, under Orochimaru, who appears in the second Naruto Shippūden filler arc.

Personality
Rinji has laid back attitude and is rarely worked up about anything. At the same time, he is shown to have sharp intellect and is a planning type. Despite his cheerful appearance, he has shown signs of having a secret agenda. He has also shown an opposite, more sadistic side.

Three-Tails Arrival Arc
After the selection battle Kabuto Yakushi and Guren held in the hideout, Rinji became Guren's subordinate. When Guren returns, 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 he analyzed his opponent's skills enough, he was ready to finish them, until he detected Shino's insect coming. Feeling the increased danger, he ordered his men to retreat.

Later, Rinji and the rest of the team come to Guren's aid when her crystal barrier is destroyed by Team 8. After retreating the team, minus Gozu, is ordered to stop Team 8 from pursuing them. Rinji uses his bats to try and catch the Konoha ninja by surprise, but Hinata's Byakugan nullifies his efforts. The battle is interrupted by the actions of the Three-Tailed Beast and Rinji and his team retreat once more.

After meeting up with Kabuto again, it is then revealed that Rinji was a spy for Orochimaru who was ordered to keep an eye on Guren. It was also revealed that he has 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 are to aid his sickly sister from a far off village. When they are once again sent to stop Team 8, Rinji does not participate, allowing his teammates to be defeated. Instead, he notices the attempted sealing of the Three Tailed Beast. When he is unable to stop it by himself, he has Guren help him and they ultimately prove successful.

After seeing Yukimaru able to summon more power then ever before to control the Three-Tails to save Guren, Rinji discreetly injures Guren to make Yukimaru even more desperate to protect Guren. Later, Rinji is put in charge of the remnants of his team to stop the Leaf Ninja again from trying to seal the Three-Tails. To aid in this matter, Rinji once again preyed on Yukimaru's feelings for Guren to make him take the strange pills and use his powers.

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

Trivia

 * Despite Rinji's troubled relation with Kabuto, they ironically share many traits; they both have spent many years acting as spy and have a knack for appearing genuinely cheerful and kind-hearted to strangers to better deceive them.
 * Rinji's personality and interests change after his meeting with Kabuto for unknown reasons.