from 4* "attack of the kutku" and from "kutku arena" are the easiest ways. if u get small blue kutku ears from "attck of the kutku" u can trade them to old man in forest and hilss and he will give back monsterbone +. and in kutku arena if u kill more than 10 kutkus yours suposed to be able to get more than 1 monsterbone+,sometimes like 7 at a time