Asagi is the tragic heroine of the Japanese video game developer Nippon Ichi. She was going to be the main character of a video game titled "Makai Wars" until it was canceled.
The character designer has a knack for becoming very attached to his creations, and rather than scrap Asagi, she ended up becoming a bonus character in a game called "Makai Kingdom."
From that point on, she has become a reoccurring character in a number of Nippon Ichi titles as a bonus or DLC character.
When she arrives, she usually complains about not being the main character, or claims that she is one. At one point her character class is even listed as "Main Character?".