I was inspired by Celtic mythology and Gaelic folklore. Namely by the Green Knight of Arthurian mythos, Green Man of Gaelic folklore and relationship between civilization (which is often lost and forgotten in lore of From Software universes) and nature.
I also took some time to figure out the Arena of our bossfight that player stumbles upon very organically during exploration of open world. There will be no quest markers or any mention of him by locals. He is very old and indifferent just like elements. Place of batte is called The Green Chapel. Inside player can find Ancient wind Instrument Carnyx.