Onyx

Onyx is a black dragon, and he has a bodyguard, Kai. He's attracted to Rose due to red dragon's power. Later, he's engaged with the blue dragon Sapphie.

Onyx acts as the antagonist of the series.

Plot

Engagement with Rose

At the beginning, he's shown captured Rose and takes her to the Tokyo tower. He's actually engaged to Rose, the necklace on her neck is the prove. After a long conversation, he convinced Rose that he Ryuji hates him, and they plan the ceremony.

In the middle of the ceremony, Ryuji stops them. Ryuji then destroys Rose's necklace, so their engagement are gone. Onyx is furious, transforming into a full dragon. Rose and Ryuji perform the "engage" so that Ryuji has the power to defeat Onyx. Using Slash Breath, Ryuji defeats Onyx.