the hakkotsu seal has very interesting ability

for one if give the person ability to summon skeletons tho there first skeleton creature is usually a pet or animal that has ability to fight this include large canine and feline type or the person could make there first creature it they are know as watcher this the person teacher as well protector for that person



two the seal also act as as summoning seal for calling skeletons of demon or angel class type as well creatures that long have disappeared from the realms.

also the third and last ability that comes with the seal give the skeletons the ability to thinks as well as talk telepathically or out loud also the skeletons also will have there memories to some point but not all of it

this also acts as a blood line seal



got the idea for the design from this story
http://www.fanfiction.net/s/4400558/1/Bone_Dancer
give it a good read