It is important to watch Soul Eater Not! Like wanna know how Sid became a Zombie? o how Liz and Patty meet Kid. Watch Soul Eater Not! It explains that. Not gonna spoil anything. I know it's a spin off series, but it takes place before the original SE Series. I say it is worth watching. It explains some character back story that the original series didn't explain much of. Like remember how an episode where Soul scared Maka cause of explaining how Sid died. Well.... Will just leave it to Soul Eater Not to explain back stories the original didn't explain. Also I believe it was in Episode 3 or...