Buried Threads by Kaylin McFarren
I'm sorry. I had to give up on this one half-way through, and it took me a month to get that far. I just couldn't get into it. I didn't care about the characters and found the plot a little confusing. They were going on a dive to find swords but yakuza were somehow involved and there was a monk who I think was good guy but was in love with a giesha who ended up "owned" by another man. Then that guy ended up dead and I quit reading.
It just wasn't for me....