Invasion of Kōhai Tochi

The Invasion of Kōhai Tochi is the term that denotes the attack Heisekai carried out on the Collective Vices, rooted within Kōhai Tochi, during the later stages of Challenging the Vices Saga. The attack was led by Yoichi Yamashin, Marshal-General of the Shuuten, with the aid of Captain-Generals Fujimoto Nakamura, Shiori Nakamura and Hiei Yamashin, along with several hundred Shinigami of the 1st, 2nd and 3rd Divisions of the Shuuten.

Cause
The Invasion began when Kaede, Queen of Heisekai, received word through her eyes and ears in Horiwari that her former bodyguard (and lover), Akira Nakamura, had been murdered by an Arrancar called Averian. She also learned that Rosuto Shiba, the second of her bodyguards, was within Horiwari also, swearing revenge against Akira's killer. Based on earlier reports, Kaede knew Averian to be a member of the Collective Vices and gave the order for the Shuuten to prepare for war.

Mobilization
It was Yoichi Yamashin who was given supreme authority over the attack, the plan that was devised and the operatives selected. He decided to take Fujimoto and Shiori (fellow Captain-Generals and Akira's siblings respectively) with him, along with his younger brother, Hiei. Together the four allies prepared their individual squads, intent to the avenge the death of their old friend and, for some, younger sibling.

Challenging the Vices
It was by mere coincidence that the Shuuten's attack occurred at the same time as the rescue attempt launched by the Rookie Six to retrieve Akiye from Shinzō's clutches. Each Captain-General encountered at least one member of the Rookie Six and after Shiori ensured their safe evacuation, the four Captain-Generals joined forces to deliver a devastating defeat to Shinzō, who barely escaped with his life.

Aftermath
The result was major loss of civilian life within Kōhai Tochi, as well as major damage to the Collective Vices and their resources, with roughly two-hundred fifty members of the Shuuten dying. Hiei, Captain-General of the Shuuten, was also captured momentarily by Bansui Amatsuki and afflicted with Hollow powers.