A large mechanical planetoid suddenly emerges from space and attacks the cities of Earth without reason or communication.

One of the Ortega pilots, known only by his call sign Fox-A, is killed in action.

His bereaved girlfriend Hiroko soon discovers his involvement in the Pandora Project which houses the Ortega's successor: the SDE-201 Aldynes.

As the invaders attack the air force housing the nearly complete Aldynes, Hiroko hijacks one of the ships and throws herself into battle in hopes of getting revenge.

[2][12][13][14][15] The game received a score of 19.56 out of 30 in a 1993 readers' poll conducted by PC Engine Fan, ranking among PC Engine titles at the number 360 spot.