The characters I've added are my original characters. For all of them, there are some details that I need to withhold because they would spoil too much about the story I am going to tell. Here's what I can tell you about them right now:
Kimi Kazuyuki - Kimi Kazuyuki is the Ice Hashira, and he comes from the Kazuyuki Clan, an original clan that I created for this rewrite. Kimi is 21 years old, and his birthday is January 23rd. Like other members of the Kazuyuki Clan, he has light blue eyes, and waist length hair that is dark blue at the top, fading to light blue at his waist. He wears a version of the male demon slayer uniform that is modified to fit his fighting style and preference. His uniform is blue-tinted, and he wears long boots with his uniform that are fitted for the snow, Kimi fights with an icy blue katana forged using the Ice Imbuing Technique.
Kimiko Kazuyuki - Kimiko Kazuyuki is the tsuguko of Kimi Kazuyuki, the Ice Hashira. Kimiko is 14 years old, and his birthday is January 13th. He comes from the Kazuyuki Clan. Like other members of the Kazuyuki Clan, he has light blue eyes, and waist length hair that is dark blue at the top, fading to light blue at his waist. Kimiko wears a version of the male demon slayer uniform that is blue tinted and paired with long boots, similar to Kimi's uniform. He also fights with a katana forged using the Ice Imbuing Technique, like Kimi. Kimiko has a crush on the Mist Hashira, Muichiro Tokito. The two of them are currently close friends and exchange letters often.
Kiroyuki - Kiroyuki is the highest ranking demon in Muzan Kibutsuji's hierarchy holding the rank of Upper Rank 0. Upper Rank 0 is a rank that I created for this story, being a rank even higher than Upper Rank 1 (the highest rank in the original). Kiroyuki is over 1000 years old. He has black hair with blue highlights that flows past his waist and glowing blue eyes with "Upper Rank 0" carved into them. He wears dark black clothing with light blue and silver ornamentation.
Mishi Mitsukuni - Mishi is a kinoe rank demon slayer corps member, meaning he holds the highest rank aside from hashira. He is 18 years old, and the older twin brother of Katsu Mitsukuni.
Katsu Mitsukuni - Katsu is a kinoto rank demon slayer corps member, meaning he holds the highest rank aside from hashira and kinoe. He is 18 years old, and the younger twin brother of Mishi Mitsukuni.