Have you seen my cat?

Some unanswered questions:
How did Jacques know Marie's name? Can he talk to her too? Is that why the cat willfully went along with the dog?
How did Miyuki steal the cat without Ken'ichi seeing it?
There is daylight for the whole of 11 panels. Jacques says: "We are going home now." Next panel is in the middle of the night. How far is that home? Or did Jacques take 12 hours to grow into a giant dog between panels 11 and 12?
How difficult it was climbing on Jacques' head? Did they use stairs? Did Jacques grow a little, allowed them to climb his head, then grew full-size?

All characters, by order of maturity:

1- Jacques
2- Ken'ichi
3- Marie (?)
4- Miyuki

All characters, by order of cuteness:

1- Miyuki
2- Marie
3- Jacques
4- Ken'ichi

Even though my friend said that disbelieving in magical dogs should be a signal of immaturity.

If you read it backwards, it is the story of a boy and a girl hanging out on a giant dog. The dog then shrinks, tells them to go home with him, accuses the girl of stealing the boy's cat and apparently steals it itself. The boy wants to go away too but the girl makes him listen her explain what exactly are the dogs' powers. He hears it all and asks if it makes her angry that he explictly does not believe in magical dogs. He invites her to hang out sometime and tries to go away again. She tells him that she must have left his cat escape from his house, apparently that's what happened last time they were together. He asks if she saw the cat, then promptly runs backwards, away from her.