One of the most powerful demon lords in history has been sealed away for a thousand years. When he finally awakens, he is reincarnated as...a 10-year-old boy?! Now under the care of the girl who released him, the demon lord Leonis must navigate the perils of Excalibur Academy!
 (Source: Yen Press)

One thousand years ago, Leonis Death Magnus, undead sorcerer and the greatest of the Dark Lords, entered magical stasis during a climactic battle. When he awakens, he finds a beautiful silver-haired young woman named Riselia standing before him. More shockingly, Leonis has been transformed into a ten-year-old boy! Now he’ll have to adapt to this strange era and deal with the twisted monsters called Voids-all while keeping his true powers a secret from his lovely new guardian.
 
(Source: Yen Press)

One thousand years ago, Leonis Death Magnus, undead sorcerer and the greatest of the Dark Lords, entered magical stasis during a climactic battle. When he awakens, he finds a beautiful silver-haired young woman named Riselia standing before him. More shockingly, Leonis has been transformed into a ten-year-old boy! Now he'll have to adapt to this strange era and deal with the twisted monsters called Voids—all while keeping his true powers a secret from his lovely new guardian. 
 
(Source: Yen Press) 
 
Note: Each episode streamed 1 week early on ABEMA. The original TV broadcast started on October 3rd, 2023.

Blackas Shadow Prince