The Burnout Inferno 2

Aizen explains that Extinguir nullifies Ryūjin Jakka, and that to wield it Wonderweiss gave up everything he had: his voice, his knowledge, his memories, even his capacity to reason. Told he cannot resist such a weapon, Yamamoto simply swats the charging Wonderweiss aside and brands Aizen a fool. He demands to know why the traitor imagines he has commanded the Gotei 13 for a millennium, then declares that no soul more powerful than himself has been born in a thousand years.

Yamamoto turns to bare-handed combat, striking with the full weight of his Ikkotsu blow, yet Wonderweiss rises again and earns his grudging respect. When the creature answers a warning only with meaningless sounds, the commander recalls that its speech was stripped away. As they trade blows he observes that not a single motion is wasted, confirming how thoroughly it was reshaped. Unmoved by its pounding, Yamamoto methodically tears off its limbs, remarks that he can now kill it without pity since it no longer wears a child's shape, and delivers his crushing Sōkotsu technique.

The eighth chapter of volume 45, THE BURNOUT INFERNO, it showcases Yamamoto's Hakuda mastery through Ikkotsu and Sōkotsu. The revelation of what Wonderweiss surrendered deepens the tragedy of his creation. The chapter was adapted in episode 294, Impossible to Attack? The Sealed Genryūsai!