Beryl lives in a world full of toys. But these aren't your ordinary toys - they're mechanical marvels that almost seem alive! And at the slightest touch, these toys 'catalyse,' that is, they merge with their owner and give them special abilities.

But not Beryl. She's a Neon Knight, and Neon Knights can't catalyse.

Beryl does have a special ability that no one knows about - she's an inventor who can turn a broken toy into an amazing, new creation. When a powerful Oxygen Knight named Coro discovers Beryl's secret workshop, she wants in on the fun. But can a Neon Knight and an Oxygen Knight ever get along?