I'm going through Kuromiya's posts on Pixiv, and there are a ton of named original characters, mostly by him. This probably isn't a complete list. The posts in pool:6395 and source:*/kuromiya-fel/14877099_* (which contain characters missed by the list below) have names written out, which will probably help with this. The characters also appear untagged in group collections like post #1320544.
- 護宮亜美
- 白柳木美門 (senpii)
- 杵月御卯
- 晴宮リア
- 風鳴美酉
- 牧里丑美
- 寅伏和
- 水空辰姫
- 槌巳実
- 蒼午漣
- 來桜未嘉
- 申木坂茶々良
- 戌天紫乃
- 冴業亥角
- 及川真歩子 (hatorin_(milkdoll))
- クローラ (dokuro915)
- 凛華 (kawabe_(kureiawin))
- 嵐宮希葉流
- 福ノ宮狐子
- 秋風未優 (akikaze_shuu)
- 寅伏楽
- 守雨紗 (minami_uri)
- 天宮薫子
- 飛宮桃
- 運宮鈴
- 色宮瑠璃
- 金宮鮮
And check on two I made on my own before I realized just how many there were:
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