When he woke up, he found himself transformed from a human into a newly hatched blue dragon, with a dragon-generating achievement system added to his mind.

While living with the Red Dragon Sister, she accomplished various feats: igniting her first dragon breath, taking her first flight, and subduing her first group of familiars...

He used lightning as his blade and wind as his wings, gradually growing from weak to strong, eventually becoming the Thunder King who commanded the submission of all races.