Shiin

was the leader of a group of bandits originating from the Land of Rice Fields, the same land where the Otogakure is located.

Background
It is revealed that there was a war taking place between the Land of the Rice Fields and some other nations, mainly due to the actions of Orochimaru. As a result, the area that the raided village was in was a de-militarised zone, ruled by no-one. The village had a gold mine in the nearby mountains, which the bandits sought, and raided the village to get to the mine.

Abilities
Being a leader of a group of bandits implies that Shiin was a very powerful shinobi. He was seen to be able to move at very high speed, such that Neji Hyūga, Tenten and Naruto Uzumaki had trouble following him. He was in possession of a unique type of kunai with long red ropes attached to the ends, which he could use with high accuracy and power. He was also able to cast genjutsu by playing on his flute, paralysing his enemies.

Menma Arc
Eventually, Shiin attacked the village. Having difficulty with getting past the wall and defeating the Konoha ninja, he resorted to using music to paralyse the Konoha ninja, but Menma countered the technique with his own music ninjutsu. This allowed Naruto to break Shiin's flute, plus Tenten and Neji to defeat the raiders.

Shiin, realising the battle to be lost, retreated to the dam at the river. He planned to flood the village to drown the villagers. The gold mine would be left unharmed. Shiin's plan to flood the village was stopped when Menma collapsed the mine. In the end, Shiin was trying to escape but Naruto manages to catch up with him and defeat him with Rasengan. Shiin was later seen tied up with the rest of the bandits.

Trivia

 * Shiin's use of the flute is similar to Tayuya's. Even the music to bind the enemy is similar to the one that Tayuya plays.
 * Shiin's name is written with the kanji for and.