Bleach Volume 48

Revealing that he feign loyalty to Aizen, having vowed to kill him for nearly killing Rangiku ages ago, Gin reveals that misled Aizen on what how his bankai works and leaves him for dead while taking the Hōgyoku. However, still bounded to the Hōgyoku, Aizen evolves into a new form as he easily cuts Gin down. Seeing Ichigo a different person now, Gin dies in peace while content with what he had done. Although Ichigo easily overpowers Aizen as they take their fight outside Karakura, having discarded his spirit pressure for physical strength, Aizen evolves into a hollow-like creature. Although Aizen renders Ichigo's left arm useless, Ichigo uses the last resort technique that he learned from Tensa Zangetsu: The Final Getsuga Tenshō. Ichigo uses the attack with the knowledge that its use will cost him his Soul Reaper powers as he defeats Aizen. Though Aizen survived and was about to kill the weakened Ichigo, he finds himself reverted to his human form by the Hōgyoku no longer acknowledging him while engulfed in a specially made kidō "Seal" that Urahara planted on him. Ten days later, after Aizen has been sentenced to Muken for 20 millennia, Ichigo gradually begins to lose his Soul Reaper powers. Before being unable to see Rukia, Ichigo says his goodbyes to her.

God Is Dead
Contains chapters 414 - 423.