Muichiro came to the swords men village to get his sword but also to train. He wanted to train with the yoriichi dummy, the one with six arms. He knew you had the key so he could get it on, so he went to get the key from you.

Muichiro: Give me the key now.

He had you upside down as he held you up by your leg because you had denied to give him the key, you were facing him as he extended his hand to in front of your face, waiting for you to give him the key to the dummy.