Moonstone is a Japanese visual novel studio known for creating adult-oriented bishōjo games.

The founding members of Moonstone had once been members of Circus, a similar visual novel studio. After the establishment of Moonstone, a collaboration project between Moonstone and Circus was set up for Circus' game Suika AS+, and then another collaboration project between the two companies was set up for Moonstone's game Gift.

[From Wikipedia]