Kōga Kuchiki sees Byakuya Kuchiki’s scarf and hairpiece and, having never met Byakuya before, concludes that he is from the Kuchiki clan, which Byakuya confirms. Kōga enquires if Ginrei Kuchiki is still alive, which Bykuya refuses to answer. Ichigo and Rukia ask how Byakuya knows about Kōga, but Senbonzakura appears and tells them to just watch. Byakuya had defeated Senbonzakura right at the start of the rebellion and, on hearing Senbonzakura’s summation, immediately recognised Kōga's abilities, having been told of him by Ginrei. They decided to work as double agents to find Kōga. Byakuya states he will kill Kōga for disgracing the Kuchiki family. Muramasa offers to help Kōga, but Kōga breaks his Zanpakutō, saying he’ll just get in the way. Muramasa, in a rage, summons the Menos he’d been keeping inside himself. Ichigo destroys several, saying he and Rukia would fight the Menos while Byakuya fights Kōga. Neither can outmatch the other in terms of swordsmanship, so Kōga switches to using Kidō, again with neither able to gain an advantage, until Kōga uses a large scale ice spell which seemingly freezes Byakuya, though Senbonzakura releases him. Kōga catches him with an immobilizing spell similar to Muramasa’s, but Senbonzakura cuts the threads. Byakuya sems to have won, but Kōga starts using illusions to confuse him, and begins to land some hits. Kōga states that he sends his Reiatsu into his enemy to manipulate their senses, and that Ginrei and Yamamoto were immune due to closing their hearts. Byakuya says he didn’t close his, because now he can kill Kōga, instead of sealing him. Koga attacks with the sealing spears and more kidō to immobilize him agin, and tries to finish the fight, only for Senbonzakura to block the attack and free him. Byakuya activates Senkei, and the two continue to battle, with Byakuya gaining the upper hand. Byakuya decides to finish the battle, and as a mark of respect attacks with Shukei. (thetvdb.com)