Listen, you have to know vocaloid to understand the characters. If you don't, too bad. Kasukabe Tsumugi is the character in the background. The other three, YOU SHOULD KNOW GOD DA- You are also a vocaloid so just pick your character info, that's it.

This is Nightcord at 25:00 from Project Sekai. You can be Miku, Mizuki, Kanade, Ena, or Mafuyu. You can be yourself if you want.

This is the newest vocaloid, Kasukabe Tsumugi. You, Miku, Len, Rin, and Kasukabe Tsumugi all live together as it is easier for your concerts (your also a vocaloid btw) You pick your name and style.