Yamata no Orochi

The Yamata no Orochi is a giant demonic dragon from the past that brought destruction to the world. It got its horn cut off by Susanoo, who sealed the dragon onto the Earth's surface with 8 magical swords. Its body is actually Japan itself. It is awakened by Onimaru and used to destroy the world, but is stopped and sealed once more by the combined efforts of a Kaguya-possessed Sayaka (who blocks his heart) and Yaiba's Supreme King Sword (used to cut off his horn).

Abilities
Superhuman Physical Characteristics, Flight, Energy attacks, Regeneration, Low-level Body Control (As his entire body is Japan itself, once he awakens his body tissue quickly covers the entirety of Japan, effectively having the entire Japan within his being),

Transformation
 * Attack: Orochi Attack Potency At least Small Country level, likely Country level (Even before transforming into his 8-headed true form, his sheer size is at least as large as Japan, if not even larger due to his body tissue overlapping the entire country. In this base form, he also created a blast with diameter comparable to his body length with a single energy blast)
 * Speed: High Hypersonic flying speed (flew from Japan to America in minutes)
 * Weaknesses: If his heart is stopped by an external cause, his body stops functioning completely, including his movement and regeneration. Loses his power if his horn is cut off.