She was mentioned to have "flowing black hair" by Yona, but never made on official appearance. She is said to have eyes just like Yona's, mentioned by Lady Iguni. She also wears tasselled earrings similar to Yona's.
It is eventually revealed that Kashi had light freckles and was rather short in stature, much like her daughter. When she was training to be a apprentice at the service of shrine, she had her long black hair tied back in a loose ponytail with a ribbon.
After the the burning of the priest's temple, Kashi was left with severe burns on the upper left side of her face, which is covered by her long black hair and also seemed like the freckles she had on her face disappeared.
Not much has been said about Lady Kashi yet. It is known that she and Lady Iguni were good friends, but soon after marrying Emperor Il, their statuses kept them apart. When Yona was born, Kashi foresaw that her daughter would be surrounded by white, blue, green, and yellow guardians. It is still believed that Kashi was killed by rebels when Yona was a little girl. However, Yona has started to question if this is true.
In chapter 192, it is revealed that Kashi was an apprentice Shrine Maiden in Hiryuu Castle. She is able to hear the voice of God, and discover’s Yon-Hi’s lineage due to her ability. Kashi is able to see everyone's future except her own.
Lady Kashi is mentioned early in the manga (unnamed at the time) having been killed when Yona was five, and her death seemed to have greatly impacted both Yona and Emperor Il. She is much later named by Lady Iguni, who recalls the time she'd visited Kashi shortly after Yona's birth.
She was the wife of Emperor Il, and her death is shown to have taken a great emotional toll on him at the time. They had only one child together before Lady Kashi's death, leaving Yona as the sole heir to Kouka's throne. Emperor Il claims that he never remarried after Kashi's death because he didn't want to place another person in danger as his wife.
Yona doesn't remember much about her mother, as she was only five when Kashi was killed in a rebel attack. Yona is seemingly very happy when Lady Iguni mentions something about her, however, admitting that she rarely heard much about Kashi after her death. Before being interrupted, Yona asks Iguni if her mother had ever said anything about her, implying that she was interested in knowing more about Kashi and what she was like.
Lady Iguni and Lady Kashi were friends during childhood, before their marriages left them unable to meet due to their newfound wifely duties. Iguni visited Kashi shortly after Yona's birth, and Kashi confided in her that her daughter had "obtained the power of the Gods". At the time, Iguni hadn't understood what that meant, but upon meeting Yona with the dragons 16 years later, she seems to recognize them as Yona's guardians that Kashi had described.
- Her name, Kashi (カシ) means "Oak".