The Cozy castle or Ōsumi castle (Japanese: 大住囲い or 大隅囲い, romanized: Ōsumi gakoi) is a type of shogi castle. It is one of the fastest castles to form; it can be completed in just three moves (e.g., in the case of Black (sente) castling to the right, K-48, K-38, G-48). It is mainly used in ranging rook openings, but it can be used in static rook openings as well.