This is the first of a six volume set called Korobokkuru monogateri. Korobburu are the Japanese equivalent to The Borrowers with distinct Ainu characteristics.
I read the entire series in the early 1980s and still have very fond memories of the books. They are still in print in Japan, and have a place in Japanese hearts like the Borrowers.
I heard about this book as a 'Japanese version of "The Borrowers"'. Like "The Borrowers", it's a book containing "little people", but that just scratches the surface and comparisons can probably end there. The two books are both enjoyable reads in their own ways, but the mood and content entirely differ.