Kami: Kami Karyuudo is a hunter sent by Kurai to kill Akuma. Kami loves to kill though, so she kills a bunch of her classmates instead. Since she didn't listen to Kurai, she was fired from her assassination work. Kami didn't really care she was fired though, she just wants to kill.
Karuma: Karuma is a guardian angel. She protects those with the curse(Shinigami and Akuma). She didn't ask for this job, she was chosen. By who? She doesn't know. What she does know is that she has to explain the curse to Akuma and Shinigami and protect them at all costs.
Kiki: Kiki Senshi is a warrior that just so happens to be a cat! She is young and quite adorable. She is very sensitive and sweet. When she's mad though, she goes into warrior mode and fights better then anyone else. It's a 110% change you will lose a fight to Kiki. Too bad she can't fight spirits.
Kurai: Kurai Riida is the demon ruler. He is the one that tries to make Akuma and Shinigami's life entirely miserable. First he sends Kami after Akuma, that doesn't work. Second he brings the curse to life to keep Akuma and Shinigami apart. Mayonaka overthrows Kurai to gain power.
Drawing of the Day: