Eager young Nono moves to the city to join the elite military team known as Topless and gets an unexpected opportunity to prove herself.

When the ambitious Tycho's Buster goes bust, she pins her hopes on a new fighting machine, but it may not work for her.

Nono begins to doubt that she'll get a Buster of her own to pilot as she heads to Pluto to salvage an old one, and uncovers a scheme in the process.

Earth's survival depends on Buster Machine No. 7.