Warship Gunner 2 is the direct sequel to Naval Ops: Warship Gunner from Koei that debuted in 2003, a subseries alongside the Warship Commander subseries within the overall Kurogane no Houkou series.
Naval Ops: Warship Gunner, a game that came out in 2003 and is part of the Kurogane no Houkou series, serves as the direct predecessor to Warship Gunner 2. This subseries also includes the Warship Commander subseries.