Now I know you wrote this three years ago, but I'd still like to let you know that I think this fic is absolutely lovely!
As a rule, I tend to be pretty critical and avoiding of OC inserts, but you managed to pull this off very nicely. I could really believe that Yasura was a lady that Houou might meet.
Made me smile!

This was amazing.
could you pretty please with dango on top write another one?

I wasn't expecting to find any katanagatari fanfics let alone finding something THIS good. I mean seriously, I'm bewildered that no one else has reviewed this so far. This fanfiction is seriously good compared to a lot of other fanfics I've seen(considering I've seen around 137859). So
grammar is perfect, I haven't seen any mistakes so far.
writing skills are perfect! The way you write, it has a taste in it that keeps the reader's attention. You choose very nice words to use. It clearly is quality writing.
portrait the characters very well. When I read it, most of the time I could create the scene and the characters in my mind. In most of the fanfics the problem is them being too occ. But this is just perfect.
lenght of the story. What else can I say? I have two stories and the longest chapter I could write was 3k before things went way out of their way. I seriously admire people who can write chapters this long.
storyline and your OC. Both very unique and original I think. Your character is neither too strong nor too weak, it is a mix between the two and really mysterious. I had fun guessing what she might be during the story, and the hints you gave also made it more enjoyable and kept me reading.
Overall, I'd say this story is one of my favorites. However, I'd also like to point out some of the missing parts in the story in my opinion.
1.I had quite a hard time picturing the girl in my head, maybe you could describe her a little more before writing the important events?
much as I like your writing style, maybe there was one too many words there and there. It isn't really attention taking, but some sentences made me quickly read past them.
I don't have much to complain about, I am really pleased with reading this story and I am grateful that someone took the time to write a good fanfiction about katanagatari. You have my respect :)
(I'm kind of sad this is a one-shot though... maybe you could do a little extra scene later, writing about what happened at a later time when those two met again?)