I have been reading fanfiction for over a decade and my tastes and tolerance levels expanded and shrunk over the years. One of the things I'm sensitive to are Original Character insertions. Too many times have I got burned by them even though concept itself attracts me so I keep trying.
One Piece fandom is one where I found not one, not two, but a significant number of OC stories that not only appear to work, but they are great fun to read. It's still a source of wonder to me.
Above them all shines this story and I'm still trying to figure out what bespelled me so.
The use of diary entries to move a plot along is done so seamlessly that it took me a while to even realize it (author helped). Each chapter leaves one satisfied with the story chunk told.
The centre piece of the story is Kim (OC) who is just a girl on the onset of womanhood, trying to do a right thing. The journey she undertakes forces her to realize that the world beyond her native island is far more different then she believed and constructed and her worldviews keep undergoing so many changes that even the sole purpose she had for most of her life starts to crumble at the edges.
That being said, all this is not at the front. You are having so much fun and laughs with unexpected, but realistic and plausible situations and people she is dealing with that it takes a while to realize itís actually an exquisite Bildungsroman.
Not to forget - there is a love story there. One where 20 chapters in neither of the pair even realizes they are interested in one another. It fits and it works. And itís not to miss if you are a Marco fan.
I warmly recommend it.