Tomohiro Hanaya, the 50-year-old manager of the gaming facility, has been arrested in addition to his 12 employees, under suspicion of hosting baccarat games with customers playing for money.
Five customers have also been arrested in the raid for betting with cash.
Police searched the property for around six hours confiscating four baccarat tables, a number of player card decks and 12.25m yen ($114,285) in cash.
According to The Asahi Shimbun, one customer reportedly told police they had intended to make money after losing their job as a result of the COVID-19 pandemic.
The illegal casino was active 24/7 for at least a year and took in around 10 customers on a typical day during the pandemic.
During the pandemic, Japanese police have conducted raids of a number of illegal gambling operations across the nation.
Last month, Aichi Prefectural Police arrested 23 workers and customers at a casino in Nagoya on suspicion of illegal gambling.
