hmm, 3 koyukkuris there, 2 enter the box, the 3rd is laying under the blanket, so it might either survive a rainstorm, if it stays there for some reason or get squashed by the mother by accident...
So not only are they even more stupid than a regular yukkuri(who could have seen the cloth flap was open on the sides) but the children even go so far as to tell each other to "please die easy."