Three-Legged Crow

The three-legged crow (Yatagarasu) is mentioned in various forms throughout the game.

Satan mentions in Lesson 30-1 that it is believed that demons derive their power from the three-legged crow, and have since ancient times.

There is also a three-legged crow sculpture at the entrance to the Devildom royal tomb, where the demon royalty are laid to rest.

Three-Legged Crow Conglomerate (Yatagarasu)
The Devildom's biggest holding company. They developed the D.D.D. (Diavolo's Devildom Device).

D.D.D.
Also known as Diavolo's Devildom Device, created by the Three-Legged Crow Conglomerate. This device is given to the MC at the start of the game and functions a lot like the cell phones of the Human World.

The D.D.D. includes its own messaging app with custom stickers. There are three mascots that are included in the stickers: Red Devil (left), Blacjak (middle), and Nancy (right). Blacjak portrays the three-legged crow and is super popular.

Trivia

 * In Japanese mythology, the three-legged crow is a mark of rebirth and rejuvenation. Historically it has cleaned up after great battles and symbolize the renaissance after such tragedy.
 * The word Yatagarasu has been translated as “eight-span crow” (giant crow) and deemed to mean Supreme/Perfect Divine Crow (the number ‘eight’ in Japanese numerology means ‘many’, ‘a multitude’, ‘perfect’ or ‘supreme’) or just “large crow”.
 * As a crow-god, it's a symbol specifically of guidance.