: specializes in visual novels, most notable for Higurashi no Naku Koro ni and Umineko no Naku Koro ni

07th Expansion

: specializes in shoot 'em ups with an abstract look. Most of their games are open source.

ABA Games

: produces a wide variety of games, from brawlers to role playing games to strategy games, most notably released Recettear: An Item Shop's Tale, the first doujin game to be distributed on the Steam platform overseas to great success

EasyGameStation

: former doujin studio that specializes in 2D fighting games

French Bread

: specializes in curtain fire scrolling shooters, most notable for Touhou Project

Team Shanghai Alice

: specializes in a wide variety of games including fighting games and platformers

Twilight Frontier

: former doujin studio that specializes in visual novels most notable for Tsukihime and Fate franchises

Type-Moon

: Creator of shoot 'em up Crimzon Clover

Yotsubane

Fangame

History of Eastern role-playing video games

RPG Maker

Event report on doujin/indie soft event Digital Games Expo

Bordersdown (formerly NTSC-UK) looks at Doujin soft fighting games

John Szczepaniak on The Escapist looks at the Doujinsoft genre