How can 你 tell the gender of a mochi?

Can somebody explain it?
*see the strip* (from the Omochi Omochi strip: link)

(follow the panel from left to right:

If 你 can't read what they're saying..

panel I: Estonia asked how can the gender be identified.
panel II: The old man has a method. I don't know what the old man exactly 说 because it's written in hiragana but he's probably asking Mochirisu if he can leave the Teddy 熊 to him.
panel III: Mochirisu told the old man to leave it there.)


How does it work? What's Mochirisu gender then, based on that method?