beta
I think "Hikaru" was supposed to protect the village from the big amount of impurities that were in the mountain. And the real hikaru's family was in charge of preventing that it got away from the mountain. But when Hikaru died, his death wish was protect his friend, not the village. So it got interested in Yoshiki and replaced Hikaru in order to "protect" him from the impurities.
Yoshiki doesn't want "Hikaru" to disappear again so his egoism is dragging the whole village into problems and soon the truth of the tombs and "Hikaru" will be revealed