Japanese. While the menus are simple, a basic understanding of "Guu, Choki, Paa" (Rock, Scissors, Paper) is helpful.
Because the game was never released outside of Japan, modern players typically access it via ISO files on emulators. 1 CD-ROM (NTSC-J). File Size: Approximately 400MB – 600MB (uncompressed). Yakyuken Special Ps1 Iso