R&D Dept. #1 (第一研究開発本部, also called R&D1 and R&D#1) was the first arcade division of Sega. It acted as the natural successor to Sega AM1, just with the Amusement (AM) moniker dropped. It also had more public presence, including its own website and social media accounts. It was succeeded by Sega Interactive R&D1 upon the founding of Sega Interactive in April 2015. The R&D website ceased many of its activities 2 months later and became inactive in early December 2017.

As a melting pot of many previous departments, R&D1 developed a variety of different products, including mobile games (e.g. Chain Chronicle, Fuuin Yuusha! Mine Tou to Sora no Meikyuu) arcade video games (e.g. maimai, The World of Three Kingdoms), medal games (e.g. Horuka x Toruka, Hokuto no Ken Battle Medal), arcade games for kids (e.g. Zukan no Tamago, Uno Challe) and other products (e.g. Toylets, Rec Check Golf).