Little D. No 2 is a tiny demon helper at the Demon Lord's Castle and is mentioned to have assisted MC with their assigned RAD tasks. It is first introduced in the story in Lesson 7-10.
Tasks
In Tasks, it appears as a battle opponent with Special Skill "SHADOW ATTACK" spelled in reverse.
Its battle dialogues also includes "CHAAARGE", "PAYBACK", "NnnNnEEeeXttTT" spelt in reverse and "coup DE Grace" in reverse word order with "DE" spelt in reverse.