An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily games of skill and include arcade video games, pinball machines, electro-mechanical games, redemption games or merchandisers. Broadly, arcade games are nearly always considered games of skill, with only some elements of games of chance. Games that are solely games of chance, like slot machines and pachinko, often are categorized legally as gambling devices and, due to restrictions, may not be made available to minors or without appropriate oversight in many jurisdictions. An arcade video game takes player input from its controls, processes it through electrical or computerized components, and displays output to an electronic monitor or similar display. All arcade video games are coin-operated or accept other means of payment, housed in an arcade cabinet, and located in amusement arcades alongside other kinds of arcade games. Until the early 2000s, arcade video games were the largest and most technologically advanced segment of the video game industry. Early prototypical entries Galaxy Game and Computer Space in 1971 established the principle operations for arcade games, and Atari's Pong in 1972 is recognized as the first successful commercial arcade video game. Improvements in computer technology and gameplay design led to a golden age of arcade video games, the exact dates of which are debated but range from the late 1970s to mid-1980s. This golden age includes Space Invaders, Pac-Man, and Donkey Kong. The arcade industry had a resurgence from the early 1990s to mid-2000s, including Street Fighter II, Mortal Kombat, and Dance Dance Revolution, but ultimately declined in the Western world as competing home video game consoles such as the Sony PlayStation and Microsoft Xbox increased in their graphics and gameplay capability and decreased in cost. Nevertheless, Japan, China, and South Korea retain a strong arcade industry in the present day.
After destroying the bioweapon known as Antares near the end of the first tournament, Shin Ikushima infiltrated the main building of Orion Corporation in an attempt to hunt down the company's CEO, Ranzou Kihara, in order to finish him off right then. However, when he went to the chairman's office, there was no Ranzou, rather, there was only a young girl inside a cryogenic sleep chamber. Shin releases the girl from the chamber and runs off. Realizing that she lacks any memory of her past, Shin decided to adopt the girl, naming her Kei. Ten years later, Kei, under guidance from Shin, grows up to become a beautiful young lady, and an accomplished black belt in Kyokushin karate. Kei still had no memory of her past prior to Shin saving her, but this did not bother her in the slightest. Until one day, Kei encounters a mysterious woman named Eileen A., who claims to be a former employee of Orion. Eileen told Kei about the Orion Corporation and how Ranzou Kihara is the one holding the answers to her past, before eventually departing, leaving Kei with nothing but questions. Several months after that fateful meeting, Orion announces the second Sentoki: Global Martial Arts tournament. Kei, along with her guardian and master Shin, decides to join the tournament to meet Ranzou Kihara and find more about her past.
