Click on the image to see full size: Click "Collide Against". Add Aiko by choosing her in the Add/Remove section. Let the whole of her be chosen. Make sure that no hair or any props are choosen too, it will slow the simulation down and in most cases break it completely. Set Collision offset and Collision depth to 0.5 and check Ignore Head, Hands and Feet if you do not want the dress to interact with these parts. You can also uncheck the Forearms and Shoulders from the collision because they do not interfere with the dress movement.