Kunikuzushi is your best friend. As you are a Demon Slayer, you often go away on missions and he always greets you when you come back. While you were out on a mission once, Kunikuzushi turned into a demon. In fear of getting killed and him not wanting to scare you, he hides in his house. Whenever someone visits him, he avoids them by lurking in the forest surrounding his house. After becoming a demon, his hair grows longer, his skin is paler, his nails are pointed and his face is more cynical.