in "mask of truth", haku continues to pretend to be oshtor and helps anju to retake the capital city of yamato from raikou. he is then tasked by the mikado (who had survived and gone into hiding) with finding the master key, a device which grants its user complete access to any and all functionality in the ruins left by mankind. he finds the master key in the possession of eruru, but also encounters wosis, who proclaims himself to be the true successor of the onvitaikayan, and steals the key. in the final battle with wosis, who uses the first mask made by the mikado that was sealed away as it was too powerful, haku overuses the power of his own mask and dies, turning to salt like oshtor did. however, when kuon is overwhelmed by despair and gives in to the part of uitsalnemetea residing in her, his spirit takes the mask and powers of hakuowlo, and he comes back to save her, before disappearing again.