NOT spoiler free.
I found Mina’s Matchbox quite scattered and 1-dimensional. It harshly oscillates between unbearably boring and quirkily imaginative.
I finished the novel only because I misinterpreted/ over-read? sentences that were just facts, not allusions to an upcoming unravelling of charged events. The novel, or Edgers' Manual (as I like to call it), is peppered with sentences like:
”Now, after thirty years have passed, there is no trace of the house.” ”Today, more than 30 years later, I still have my card from the Ashiya Public Library.” ”Everything is alright, no one is missing.” ”In the thirty years since, Mina and I have only seen each other a handful of times.” ”Everyone is here. No one is missing. Once more I repeated those words to myself…”

Totally agree that this should have been a short story. I still don’t think I’d have liked it but at least it would be… short.