Thanks for the question!
It's a sequel. They are very different games; the first one was sort of complex visual novel. But this is a complete RPG with battle and character stats and gearing. It's *significantly* bigger and (I think) more fun than the first game.
Also the story is new. It takes place at a later part in the main hero's career, after they've made a name for themselves. Some of the characters from the first game reappear... And I'm hoping one or two more will make an appearance in the next chapter :).