Nitroplus, sometimes written as Nitro+, is a Japanese visual novel developer that has developed a number of visual novels, including eroge. They have been collaborating with TYPE-MOON (another developer) to create the light novel series, Fate/zero. They also have a branch of the company called Nitro+Chiral, which focuses on BL visual novels. Their works usually have dark themes such as reanimation of the dead and murder.

Twitter: @nitroplus_staff