Otogakure Symbol.
Otogakure (音隠れの里, Otogakure no Sato, literally meaning: Village Hidden in Sound), called Oto for short, was Orochimaru's personal village, founded for the express purpose of collecting ninja for his experiments and his quest to learn all jutsu. In actuality, Oto is not really a village, but a group of hideouts and bases scattered throughout the Land of Sound and other countries. Sound ninja use a diverse amount of jutsu, which are mostly centered around modifications and mutations Orochimaru gave them.
Three Sound ninja (Dosu Kinuta, Zaku Abumi, and Kin Tsuchi), under Orochimaru's orders, entered the Chūnin Exam with the goal of killing Sasuke Uchiha. However, Orochimaru was actually using them as test subjects for Sasuke's power after Orochimaru gave him the Cursed Seal. Later, Otogakure assisted Sunagakure in invading Konoha. With Orochimaru being sealed by Itachi Uchiha, the fate of the village is unknown.
Orochimaru base of operations
Orochimaru's primary base of operations, is an underground compound where Orochimaru can carry out his
operations. The pathways inside the compound are marked with varied booby traps, including spiked pits, water traps and passages leading to rooms housing his evil experiments. Portions of the village was destroyed by Uzumaki Naruto and Jiraiya, when they came to find Hidden Sound's location. At this point Orochimaru had abandoned the compound, it is unknown where he has since moved.
Invasion of Konoha
Sunagakure had for years suffered a series of budget cuts by the daimyo of the Land of Wind, weakening the village and
thus rerouting ninja missions to Konoha. Orochimaru, the leader of Otogakure, had years earlier left Konoha after having not been accepted for the position of Hokage. With both villages having vendettas against Konoha, Orochimaru approached the Fourth Kazekage with the proposition of a joint invasion. Orochimaru would at some point assassinate and impersonate the Kazekage to make controlling Sunagakure easier, so it is unclear how much of the plan was his idea.
The attack was meant to be fought on two fronts: Sunagakure's jinchūriki Gaara would make it to the final rounds of the Chūnin Exams taking place in Konoha and would release the One-Tailed Shukaku from the center of the village. While Konoha was preoccupied with Shukaku, Sunagakure and Otogakure forces would break through the walls surrounding the village. Orochimaru, having only one goal for the invasion, would fight and kill his old teacher and the current Hokage, Hiruzen Sarutobi. Though Konoha never knew the exact details of the invasion or who would be invading, it suspected an attack and had its forces prepare for the worst.
Land of Rice Fields Arc
After recovering from his battle against Sasuke, Naruto joins Sakura in another attempt to save Sasuke. Before crossing Konoha's border, Jiraiya appears. He saves them from becoming labeled rogue ninjas from leaving the village without authorization by allowing them to join him on a mission to gather information on Sasuke and Orochimaru. Their journey takes them to the Land of Rice Fields, the home of the Otogakure.