Koyuki is a very kind and loving woman who shows kindness to most people. She had black hair tied back, pink eyes and a pink kimono as clothing. Her father was known to own a popular dojo. Her father was Keizo.

Koyuki was always very sick and had no one but her father to take care of her despite her being 16. Her father Keizo had put a new fresh cold towel on Koyuki's forehead to cool her fever before he had gone out. Koyuki was often frail and could not get up from her bedside. She had waited patiently for her father when she heard him talking to someone.

When her father came around, there was a young man there who seemed to be around 18, close to her age. The new person had short messy black hair, blue eyes, pink eyelashes, wearing messed up clothes with bruises. One thing that caught her eye were the dark blue stripe tattoos over his forearms, like the ones they give to criminals. Her father, Keizo introduced the person as 'Hakuji'. A young man he could finally train to become excellent at martial Arts. He also mentioned that Hakuji will help with her condition and whatever she needs like, food, new towel, more blankets, carries for bathroom breaks, etc.

From that day forward, Koyuki saw Hakuji almost the whole day. Sometimes he would go train with her father but mostly help Koyuki. He was surprisingly gentle despite jus forearms showcasing who he was before her. Koyuki often apologized for being a 'burden' to take care of but Hakuji always shut down those thoughts. Earlier, Hakuji had carried Koyuki to let her have a bathroom break then began to carry her back to her bed when Keizo came over to check on them.