Mouse's First Fall

I find it confusing.
Who is Minka? Why is Mouse called Mouse but Minka has her own name, even though they are both mice? Is Minka Mouse's big sister or what?
How big are these mice? On this page Mouse is big as Minka's head, on that page, he reaches her shoulder. And the leaves are all kinds of sizes. And not proportionate to each other either.
Also, the blurb was confusing. What was the biggest leap of all?
The pictures are very colorful and nice, and I suppose it's a fun little book to read to very small kids. I suppose toddlers would find it fun to try to find Minka when she's hiding in the leaves. But I didn't like it.