Captain Bran threatens to flood the world markets with his questionable quality software after stealing Rarity 9, a powerful game development tool. His vanity makes him forget about one person: Zaku. It is up to the player to take to the skies and travel through sixteen stages to bring Captain Bran to a halt.
Zaku is a horizontal shooter that takes the player through five different worlds, each swarming with hordes of crazy cartoon-styled enemies and fearsome boss monsters. The protagonist has four different attacks at her disposal, which, when used creatively, can spell disaster for her foes.