So FINALLY I found out who Minka is! She is Mouse's big sister. It wouldn't have taken too much to say it in the Fall book. “One cool fall day Mouse and his sister came out to play!”
This book follows the formula. Mouse goes around and spies things that are somehow connected to Valentine's Day. This time he follows his big sister around the house and the sister finds things and Mouse wonders what they are and what the big sister is going to do with them. I like this better than the Halloween book, but not as much as the Christmas book. The illustrations aren't quite as nice in this one, though.