This is an FM Remix of the Space Harrier theme produced exlusively for this bios screen. The JPN Bios Space Harrier remix gets to use all the available sound channels on the SMS at once, because it doesn't have to handle the sound effects for the game. The stars dance to the tune.
The JPN Space Harrier 3D had a similar, but different, FM remix:
Sega was always great at bios screens, the Sega CD US Model 2 bios is probably my favorite of theirs:
But the JPN SMS Bios is probably the most SEGA start screen ever.
For comparison, the normal Space Harrier SMS music using the PSG only:
The Japanese SMS has the FM Unit built in, unlike the Mark III, hence the bios screen.