Cusack

Cusack is a high-ranking demon in The Seven Deadly Sins anime (appearing primarily in the later seasons, such as Imperial Wrath of the Gods / Kamigami no Gekirin and the final season).

He is one of the most elite and ancient demons in the Demon Clan, serving as Zeldris's former master and swordsmanship teacher. Cusack is deeply devoted and protective toward Zeldris (often calling him "master" or "lord"), showing almost paternal loyalty, even though he is far older and more powerful.

Physically, he appears as a tall, muscular man with distinctive hot pink/red hair in a long braided ponytail, a prominent long mustache, and a goatee, along with his demon mark.

He is renowned for his immense strength, masterful dual-swordsmanship, and terrifying abilities like mind control (via techniques that force obedience or cause death on resistance), earning him nicknames like the "Napping Reaper" or "Slumbering Reaper."

Cusack shares a unique origin with Chandler (Meliodas's former master): the two were originally one being, the "Original Demon" (the Demon King's primordial creation), split long ago after a rebellion. In the anime's climax, they merge back into this overwhelmingly powerful original form.

Overall, he's portrayed as a confident, overpowered antagonist whose presence alone inspires fear, and his actions revolve around advancing Zeldris's role in the Demon King's plans during the revived Holy War.