Joint pixiv account of twin artists.
Kawazuishi[Sumire]'s posts have commentaries with ★ at the beginning of texts.

Artist name (1): 蛙石(Air) (Kawazuishi[Air]) (reading is a best guess)
Artist name (2): 蛙石(すみれ) (Kawazuishi[Sumire])

See also

• Pixiv account: http://www.pixiv.net/member.php?id=1346777