hmm, doesn't seem like an ax to me, not a tragic ending or anything like that, so it's ok. I would've liked him and the Hiyoko girl to pair up in the end (maybe the author will do a side-story, who knows) and an after-image of Nico somewhere else, a place where she watches over...or something like that yeah? But this feels like he somewhat confused the ending, would've been better if it showed him and Hiyoko starting a new life or a more polished version of the ending, giving importance to how each character ended up, I mean, Hiyoko n all didn't get much closure, so I hope the author works on such errors in the future works.
Anyway, I don't regret this one bit because this series gave another artist whose releases I should look out for, thank you Kajimoto Akari, I'll look forward to more works from you. And I am gonna keep my hopes up for a reboot or a side-story since you did it for the 'slit-mouthed woman' series...