No, it's based off of a manga. I've read a couple. Basically their was this big group of 5 vandal busters who were the strongest. Beet, is the leaders(the one with the big sword) little brother. The king of vandals comes and Beet gets involved and gets killed. The 5 Vandal Busters put their souls inside of him to bring him back to life. But, they also give him their saiga(which is a vandal buster's greatest weapon. It's only supposed to come out when they need it the most.) So in whatever situation Beet is in, he can summon one of the five saiga. But, in the 2nd manga it seems he can summon anyone of them at his own will. The marks on his chest represents what level vandal buster he is. You kill the vandal, report back to the lady, she gives you money and puts a mark on your chest. The more marks, the higher your level is. I hope this helped you out a little.