SEIBU KAIHATSU INC. was established in 1982 as “Seibu Denshi.” It is said that the name was taken from the Seibu Lions, who became Japan's number one professional baseball team that year. In 1984, the arcade game division was separated and became “SEIBU KAIHATSU INC.” Additionally, in 1991, the development division was separated into “Rise Corporation.”

SEIBU KAIHATSU INC.'s most famous work is the vertical scrolling shooting game “Raiden,” released in 1990. This game was a big hit among arcade game fans and became a series. However, around 1999, key development members left the company, and the official website disappeared. After that, they established the strip mahjong development division “Cats” and changed the direction of their business.

The “Raiden” series was subsequently developed by MOSS, founded by former development staff member Toshiaki Komazawa. In 2005, MOSS developed “Raiden III,” reviving the SEIBU KAIHATSU INC. name and showing fans that they were still active.

SEIBU KAIHATSU INC. has released games in various genres, not just vertical scrolling shooting games. Their unique development style in the strip mahjong field is particularly notable.

In recent years, SEIBU KAIHATSU INC. has also entered the smartphone game business and continues to take on new challenges. This allows them to utilize the know-how they cultivated in arcade games and bring their charm to modern gamers.

SEIBU KAIHATSU INC. has continued to be loved by many gamers through its long history and challenges in various genres. The success of the “Raiden” series and their shift to strip mahjong, as well as their constant search for new paths, highlight their charm. We look forward to SEIBU KAIHATSU INC.'s new challenges in the future.