Asuna Watase's father is a minor character in Children Who Chase Lost Voices. As her father, his name must be Watase (渡瀬, Watase).
Background[]
Watase was an Agarthan and the mentor of Shun Canaan Praeses. He later settled on the surface and married a Topsider woman, whom he had a daughter with. A few years later, he passed away.
He owned a piece of the Agartha's clavis, which he passed to Asuna as a keepsake.