Kazuki's mother is a tall and very beautiful young woman with wavy mid-back length burgundy hair that is swept to the right, magenta eyes, a mole next to her left eye and hot pink lipstick.
Kazuki's mother is a quite nice young woman who really seems to care about her biological son, even though it is unknown on why she did not raise him.
She greets Haruka Yasaka when she meets him, and even after the latter tells her to leave and never come back, she smiles back saying that it will be okay.
Kazuki's mother only appears in flashbacks of the Yasaka siblings. One day, she meets her biological son and hugged him. They both talked about their new life and they both agreed to meet at the train station. However, after losing her sachet, Haruka found out about her and tried to stop Kazuki from joining her. That left her taking the train alone without saying good bye to her son.
In Episode 7, Kazuki wants Haruka to keep her sachet, saying that he will meet her after he'll connect to the people close to him.
She is Kazuki's biological mother whom she met at the station and she had a scent that Kazuki recognizes.
Kazuki mentioned having "an adorable little brother" who met Haruka not long after meeting Kazuki. Even after being rejected by him, she told that it will be okay.
According to Akiko Morishima, she and Haruka's mother have a connection.