Kara's Footprints

Synopsis
In Amegakure, the Team 25 genin report to Sai and Sasuke the found the alleged Kara hideout based on the information Sasuke acquired from Shojoji. The building used to be a sewage treatment facility, until it was abandoned due to a toxic gas incident that caused several fatalities. They also hand them a map of the waterways. Sai congratulates them on their intelligence work, and requests them to notify the nearby Anbu teams that he and Sasuke will continue alone. Sai notices that rebuilding hasn't progressed in Amegakure. They venture inside the building, and are watched by someone. Sai and Sasuke trigger a trap, exposing the one watching them and subduing him. The man accuses them of killing his friends. Sai tells the man they're Konoha shinobi, and Sasuke asks to hear the man's story, as the ones who killed their friends might be the same ones they're looking for. The man introduces himself as Garashi Tōno. He explains he learned ninjutsu from an old man who raised orphans like him who lost their families during wars. Garashi isn't sure when Sai asks about Kara, but recognises the name, and shows them a design he copied from them. They investigated them when Kara showed up, glimpsing something like an experiment, but they were spotted, and all but him perished to poisoned gas. Parts of the building collapsed behind him, but Garashi is sure that there are still places with the gas. Garashi asks why it took the Land of Fire so long to act if this is something in their interest. Sasuke asks Garashi to take them to Kara's hideout. Garashi asks them to help him recover his friends' remains in return. At the hideout, Garashi warns them not to wander in side paths, and that depending on the airflow, the places with poison gas changes. They arrive at a blocked passage, which Sasuke breaks open with Chidori. Garashi rushes in. Sasuke and Sai follow him, and when they find Garashi on the floor, they're caught in a trap as gas begins filling the room. The real Garashi appears with a gas mask, and reveals he killed his friends with the gas because no one would save them, but Kara offered him hope. Garashi leaves them to pass out, and considers releasing more poison to deal with their allies. Sasuke and Sai show up, the ones Garashi trapped being clones. Sai explains he was careful avoiding dangerous areas along the way, but rushed in near the end, and though getting close to his friends would make him emotional, Sasuke noticed a strange calm to him. Garashi tries escaping, but begins to suffer the effects of the poison gas. Even if Kara wants him to die, he refuses to let Konoha learn anything, and kills himself. The building begins to collapse, so Sai draws a bird for them to escape. They spot some of what remained from experiments, but can't investigate. They conclude that not only they confirmed that Kara actually exists, but also that they have sympathisers. Back in Konoha, they report to Naruto and Shikamaru. Sasuke adds that Kara's experiments are likely biological, as he's seen similar equipment when he was with Orochimaru. Sai asks if Naruto saw Ino's report on Katasuke. She was able to determine a third party had been influencing him. Naruto wants to reinstate him, as testing without him has slowed down considerably, something they can't afford when their work has been leaked. Kara holds a meeting, where its leader reports the destruction of their old facility.