I'll start off by saying that Kingdoms of Sin is a great story. If you get nothing else from this review, at least keep that in mind.

It shines in many places, though I'll start first with the characters. Amako and Tyffeon are an amazing main duo. Amako's attitude and jests mix perfectly with Tyffeon's tsundere self. They bounce off each other in ways that make both of them very endearing. It's like witnessing the banter between a couple that won't admit they are one yet. The side cast really shine through as well, and a decent amount of work goes into fleshing them out well.

The world and story are no slouch either, and easily matches up to the characters that inhabit them. Lore is dripped in bit by bit as they explore, and Amako's exposition feels natural. Nothing really felt shoehorned. The various regions that the story describes feel like actual lived-in locations. The stakes made sense, and the motivations matched them just as well.

The only thing that I would nitpick is the language and the prose, though they are secondary to making a great story. They didn't detract too much from the experience.

To summarize, please give this a read if you enjoy fantasy and the exploration of characters and their relationships (even if things can get sad at times). It would be a sin to not give this a try!