Sports bra (?) and sports bottoms.

Justice!!

Justice!!

Simple skirt

Underwear and skirt.

A troublesome decoration

Tie a part

Stick the part you tied through the skirt

The parts are colored differently to make it easier to understand

Tie the string you stuck through so that it intersects with the other one

On the inside of the skirt, tie the blue string to the red one and then pull it through the hole.

Then you can just repeat the process!!