In the Playstation version, the mission complete screen has the game's title misspelled. It says TunderForce V.
The "Perfect System" subtitle was only applied to the PlayStation version of Thunder Force V. Why? Because the PlayStation version offered several improvements over the original Sega Saturn version, including slightly faster speed, a true final boss, extra bonuses, and analog control. Thus, the PlayStation version was the "perfect" Thunder Force V.
The Thunder Force series stretches as far back as the MSX home computer, a computer system which only saw the light of day in Japan and Europe. Three sequels (II, III, and IV) were released for the Sega Genesis console in the 90s. TFV was released on the Sega Saturn first, then was ported to the PSX, which was the only version of this game to be released outside of Japan.