Metatron (A Cruel Angel's Thesis)

Metatron is one of the Seraphim, God's first and most powerful angels. He was also at one point the Scribe of God and the Chancellor of Heaven's day-to-day-administration, and was known to have fought in the Great War between the Three Factions. Although he survived the war, he disappeared from Heaven at an unknown time to lead a normal life among humans, chiefly being interested in the history, tactics, and ethics of ninjas, although he also likes human literature and is well-versed in it too.

He may or may not be the main protagonist and viewpoint character of a story that won't ever be a thing.