Because the bucket lies below the hallway, there are no worries about whether the soil will get flushed away by the rain.
The underground is warm even during Winter; now the measures for coldness prevention might be enough.Using broken planks as the material, I made some donut-shaped planks, and installed them onto the mouth of the bucket.When looked from the outside, it appears to be a sandy mountain which is often found in sand yards, with the insert of leftovers and the doorway for yukkuris present. Then, bury the plastic bucket below the hallway again, and cover all the exposed side of the bucket with soil, with the exception of the openings.In this way the doorway for the yukkuris was resized to meet the minimum requirements.
Not only did it reduce the work yukkuris need to block the entrance, it also reduced the gap from which the cold wind would slip in.The next one to take care of is the entrance of the bucket, or the yukkuris' doorway.
It was too large for yukkuris whose bodies' diameter is at best 30 centimeters.After that, install a hinge and a buckle on the opening so it can be opened from the outside.Yukkuris will get their nest sealed up during Winters,
so I made this opening as the insert of leftovers in that situation.First, dig out the plastic bucket, lay it down and cut a small square opening on the side which was used as the ceiling.