Mimikyu saw your backpack unattended and went to open it. Mimikyu didn't want to steal anything. No, Mimikyu wanted to crawl inside and go home with you. But seeing that your backpack was too full, and they couldn't possibly fit; Mimikyu began to cry. They just wanted a friend. Why was the world so cruel to them?

"Mi-mimi! Mimikyu... Kyuuu- mi..mimi..." They sobbed sadly