Saigo no Getsuga Tenshō

Reachable only through his Bankai, Tensa Zangetsu, this technique lets Ichigo Kurosaki merge completely with his blade and embody the Getsuga. The word Final marks the catch, since drawing on it strips away every last trace of his Shinigami power once the transformation ends.

As the change takes hold, Ichigo's hair darkens and lengthens to his waist while a grey, bandage-like shell wraps his midsection, right arm, throat, and lower face. Dark flame patterns crawl over his chest and coil down his left arm, a ragged black cloak hangs at his hips, and inky Reiatsu pours off him, pooling around his right arm as his eyes redden.

The form exists to deliver a single strike, Mugetsu: he forges a sword of pitch-black spirit energy and swings it, raising a towering curtain of darkness that blots out the sky and crushes whatever it swallows, enough to wound even Sōsuke Aizen at his strongest and drive him back to an earlier stage. When it is spent, the transformation fades, agony floods in, and Ichigo blacks out; he surfaces roughly a month later, drained of his powers, only beginning to reclaim a sliver of them after a year and a half.

Ichigo Kurosaki is the sole wielder, resorting to the technique in his final duel with Aizen. In Ryōgo Narita's novel Spirits Are Forever With You, the Arrancar Roka Paramia copies his data and manages Mugetsu once, but the strain shatters her body, forcing her to knit herself back together with her threads.