Because you are running a Japanese region ISO, you will need a Japanese PS2 BIOS dumped from your console for maximum compatibility.
Whether you are a long-time fan wanting the uncensored blood or a newcomer curious about the roots of weapon-based fighters, tracking down this specific ISO is worth the effort. Just remember to set your emulator to 60Hz, turn off all post-processing filters, and embrace the spirit of the sword. Samurai Spirits Zero PS2 ISO -JPN-
: Includes 24 playable characters , featuring 20 returning favorites and 4 all-new characters : Yoshitora, Kusaregedo, Yunfei, and Mina. Because you are running a Japanese region ISO,