Artist claims on their blog: http://rusianhumi.blog25.fc2.com/ to go by this shorter name now, per this explanation:

"Author:文月留志亜
最近は「フミさん」で統一してます。なんかめんどくさくなｔｔ（ｒｙ"

Can't parse the 文月留志亜, thus using Fumi-san as noted. Same name as on Pixiv as well.
fumi-san (artist)