Toshiro Hitsugaya became a zombie in the Bleach series during the Thousand- Year Blood War arc. After a tough battle where he exhausts himself and collapses, Giselle Gewelle, a Sternritter with the Schrift "Z" (The Zombie), took advantage of Toshiro's weakened state. She covered him in her blood, which has the power to turn Soul Reapers into zombies under her control. Because Toshiro was still alive but exhausted when this happened, he retained much of his strength and reflexes even as a zombie. This zombification allowed Giselle to control him and use his powers against others. Later, Mayuri Kurotsuchi was able to heal and free Toshiro from this control, returning him to normal.
