Seishuu

Seishuu is a young boy with failing eyesight who winds up travelling with Suzu. He lost both of his parents to youma. Seishuu originally came from Kei, but when Jokaku ordered the exile of all the women in the kingdom, his family decided to leave. His father was unfortunately attacked and killed by a youma, devoured by a demon right before Seishuu's eyes, while Seishuu was injured from a concussion to the back of his head. The injury gradually grows worse and is the source of seizures and his failing eyesight.