Arc 4Exile to Hueco Mundo
Yan Si was imprisoned amid Kuchiki Kyōka’s rebellion, then sent to Hueco Mundo with a Shinigami expedition after helping expose the crisis. The expedition was devastated, Ashido was left behind, and Yan Si prepared to return to Hueco Mundo with Captain Kenpachi.
- Urahara Kisuke visited Yan Si in the Maggot's Nest, where Yan Si funded a tool to help him understand his Zanpakutō and Bankai while they discussed the Nobles’ conflict.
- Kuchiki Kyōka escaped with Muramasa, killed three conspirators, and later turned against the Nobles, while Yan Si tried to restrain him and warn him that others were exploiting his rebellion.
- Yoruichi Shihōin and Captain-General Yamamoto defeated and sealed Kuchiki Kyōka, while Yan Si fought Tsuzurimono Bansho and learned that his Zanpakutō was not the Scroll of Wind and Snow.
- Yan Si returned to the Maggot's Nest after helping stop the fighting, and Captain-General Yamamoto commuted his prison sentence to service in the Hueco Mundo subjugation force.
- Yan Si concealed the expedition’s camp and led his squad away from a massive Hollow horde, then diverted the Picaro from the camp while Cronos Elibird attacked the remaining Shinigami.
- Kurayashiki Kenpachi fought Cronos and used Bankai to swallow him, but the camp was buried in a sand vortex and its survivors were scattered.
- Yan Si reunited with Kurayashiki Kenpachi and the buried squad, led the Picaro through the sand to rescue Ashido and the others, and guided them through the Senkaimon.
- Szayelaporro captured Ashido as Yan Si escaped through the closing Senkaimon, and Yan Si learned that reopening the gate would take months before deciding to return to Hueco Mundo with Captain Kenpachi.