Excellent story. The tone works really well. It's dark and gritty. I could almost feel the coldness and sense of loneless. It has that The Road/The Last of Us vibe.
However, I think that the relationship between the two characters could have been more explored. One more chapter--in which we would see them living together and getting to know each other--would suffice. As is, we just don't give a rat's ass care about Helen.
The way Leiki defeated the "monster" (more on that in that spoiler section) didn't feel like deus ex machina to me. She was, in a way, trained to do this (and got lucky). Or...
So, the monster that drove everybody out, thus transforming a whole town in a post-apocalyptic scenario, was a bear all along? Or was Leiki the Monster? I interpret that she somehow bit and twisted the bear's neck while it was attacking her coat. I also didn't understand why Leiki said that would fuck Helen if she had the strength.