Tsuchimikado Harukage

A renowned onmyouji and friend of Princess Hatsune during the Sengoku period.

Spoiler

As a descendant of one of Hatsune/Sato's former benefactors, he helped her make her way to Taishima, an island rumored to be home to mermaids.

Kuki Sumitaka, looking for a solution to the Curse of the Raging Waves, turned to Harukage. After conducting an investigation, Harukage concluded that it would be possible to seal the sacred land by offering up a sacrifice, thereby suppressing its calamitous effects. With Princess Hatsune's noble sacrifice, the storm at last died down, and peace was restored to the seas around the island.


Harukage was also able to seal the Curse of the Forsaken Fish in the wooden accessory that Princess Hatsune had been wearing, turning it into a curse stone. Harukage used the resentful memories contained within the curse stone to create a record of the event, which he sealed within a heavily-locked iron box before concealing it in a rock on the seabed. In the event the Curse of the Raging Waves had not abated even after 400 years, he made it so that the seal on the rock would be lifted at the same time as the seal on the sacred land, so that the record of what had happened and the method of undoing the curse would make its way to future generations.