During the course of the game, you are given the opportunity to rescue Izumi, Miki, and the Makimuras. Rescuing some or all of these characters can trigger different endings - and allow additional levels - in the game. The "bad" ending ends the game at the end of Level 6. The "moderate" ending allows a seventh level. The "best" ending only differs from the "moderate" ending in that it gives a better ending to the storyline as a whole.
Ending How to unlock
Bad Ending Fail to rescue Mr. Makimura, Mrs. Makimura, and Izumi.
Best Ending Rescue Miki in addition to Mr. Makimura, Mrs. Makimura, and Izumi.
Moderate Ending Rescue Mr. Makimura, Mrs. Makimura, and Izumi.