Restraint of Zero shmup demo v2.4c -- stuck on stage 4

[PC Engine Fan X!]

I thought that this little doujin PC shmup demo of "ROZ: Restraint of Zero" version 2.4c had just a single stage to play with. It turns out that it has five seperate stages to play through with different viewpoints to contend with (horizontal side-scrolling viewpoint mode, classic Space Harrier viewpoint mode, and that famous vertical top-down viewpoint mode).

Am currently stuck on Stage 4 where you have to defend a space station from the usual small fry enemies and assorted asteroids pelting the player down but the HP meter of the space station still reaches zero and I still get the dreaded "Mission Failed" screen over and over again. Any helpful suggestions on how to properly beat this particular stage and proceed on to the fifth and final stage in this ROZ shmup demo?

The low-res 320 x 240 overall graphical presentation of ROZ looks great and reminds me of the early PSX games era in terms of blocky polygonal graphics. The stark black polygonal female sillouette placed against a white background with black tiles streaming past is a very simple but effective aesthetic presentation. Sometimes, such minimalistic & simple polygonal graphics does the trick...as with the case with this opening intro of ROZ. ^_~

PC Engine Fan X! ^_~