Doko Demo Issyo (どこでもいっしょ, Together Everywhere) is a 1999 Video Game developed by Bomber Express and published by Sony Computer Entertainment Inc. for the PlayStation, released on July 22, 1999 in Japan. Doko Demo Issyo was one of the games that used the PocketStation; it was instrumental in making the device sell so well in Japan. It is the first game in the Doko Demo Issyo Series. Doko Demo Issyo is a communication game, a game where you interact with the characters through words and phrases. The player can choose from five characters known as Pokepi and interact with them in an apartment. They can be taught words, and the player can answer questions asked by them. The biggest feature of Doko Demo Issyo is its compatibility with the PocketStation, a handheld device that often came packaged with the game, and its reliance on the device made the PocketStation required to play the game. It allowed the player to take any of the Pokepi with them anywhere, and they can continue to interact through the device. A remaster of the game was released on the PlayStation Portable on December 7, 2004 for the franchise's 5th anniversary. A port of the original game, separate from the remake on the PSP, was also released on the Playstation Vita in 2013.

Doko Demo Issyo is often described as a Virtual Pet game, but unlike many games of that genre, Doko Demo Issyo includes a communication element. When the game is started, the player inputs their name, gender, blood type and birthday and chooses one of the five Pokepi to live and play with. The setting of the game is a small one bedroom Japanese apartment. It contains various comfort items like a refrigerator and a television set with a game console connected. The floor of the room is covered with Tatami mats, and the Pokepi will sleep on them when they are tired. There are two other rooms of the apartment, a small restroom and a bathroom. There is a radio that they will sometimes listen to too.