Tannin  

Blaze Meteor Dragon, タンニーン

The Blaze Meteor Dragon, also known as the Sacred Blaze Meteor Dragon (魔龍聖（ブレイズ・ミーティア・ドラゴン）), is a former Dragon King who reincarnated and became an Ultimate-Class Devil. He trained Issei in the mountains to help him attain his Balance Breaker status.