Prototype is a game developer that broke loose from INterchannel (old NEC inter channel) in 2006. They concentrate on porting "girl game" computer games to home video systems.
Prototype Ltd. (株式会社プロトタイプ Kabushiki kaisha Purototaipu) is a Japanese software company established on March 27, 2006 by Toshio Tabeta, a former producer of Interchannel. While still with Interchannel, Tabeta's team was responsible for mainly developing and publishing versions of visual novels originally published by VisualArt's for consumer platforms like the PlayStation 2 and PlayStation Portable. After Prototype split off from Interchannel, the company still continued to work with VisualArt's. Prototype is also involved in producing mobile phone ports through VisualArt's Motto which Prototype manages. Prototype has also produced a set of drama CDs based on Key's visual novel Clannad.
Source: Wikipedia, "Prototype (company)", available under the CC-BY-SA License.