Edit: Just noticed that the artist wrote "Mai" instead of "Mei" twice in the first page so I fixed. Not sure it was worth the update but might as well.
I was planning on waiting for this to be finished before posting it, but the artist has gone radio silent for almost a year now (hope they're okay). That's too bad since it now ends in such a tease.
Note that: - The 3 (or rather 4) first pages are the prologue. The main story start page 5. - I'm the one who edited the text in the images, since they are originally separated. You can find the textless version here: /g/2929285/e5943409d9/