The Dōkyūsei series (同級生?, lit. Classmates) is a series of popular eroge by ELF. The original Dōkyūsei (also called Nanpa, meaning "pick-up", due to its batch file name "nanba.bat"), released in 1992 for the NEC PC-9801 microcomputer, is generally considered to be the first dating simulation. It was followed by three sequels: Dōkyūsei 2 (Nanpa 2) and Kakyūsei (下級生, meaning Lower classmates), both of which were also very successful. There was a four-episode OAV made from Dōkyūsei, a 12-episode OAV was made from Dōkyūsei 2, and both an OAV and TV series from Kakyūsei. In 2004, ELF released the next in the series of games, Kakyūsei 2.
A Game Boy Color mahjong game with Dōkyūsei 1 characters called Jankyusei (雀級生) was also created. The Dōkyūsei 2 expansion disk (Nanpa 2 Special), Dōkyūsei 2 SP, was also made into an OVA, this expansion is also referred to as Sotsugyōsei (卒業生, meaning The Graduate).
There is a persistent rumor of a Dōkyūsei 3 being planned by ELF, and a large fan demand for it. According to tinamix's review, Dōkyūsei 3 planning appeared on several eroge magazines after they had released Kakyusei. However, ELF seems to have no concern for it as of 2006, and Masato Hiruda, the great scenario writer of Dōkyūsei sequels, retired as CEO of ELF as well in 2000.
"Dokyusei" is a Japanese word which means "classmate". However, not all the girl characters are classmates of the main character. The others are characters that the main character can meet in the city (e.g., Dokyusei 2).