Tsuyoshinzoku

Tsuyoshikō (剛コウ) was a top-tiered dragon that served as one of the four members of the Shiryū (四竜, Four Dragon Kings). He was later killed by and assimilated into Yūmei Kokūzō.

Appearance
Tsuyoshikō's scales and wings adopted the appearance of obsidian, like the other Shiryū. His main elements being lightning and illusions, his body appeared to be manifesting a storm of dreamlike-lightning.

Abilities
As a top-tiered dragon, Tsuyoshikō possessed a cataclysmic reservoir of chakra. He was a master of both Lightning Release and Yin Release, capable of producing lightning storms, and even thunder itself, all while concealing himself away in the clouds of his own generation, or simply inducing astraphobia upon the unwary.