Baby: Mommy stop! / Don't forsake me! / Reimu doesn't wanna die! Mom: I know, baby... / Reimu will never abondon my baby... / But... a little... just a little while... baby: Yuaaaa!! Stop it!!
>>still not judging Been there, done that, nobody changes their views, discussion pointless. Wastes the time of all involved. Don't bother starting something.
Why do you care about "the asshole who put them there" in the first place? Yukkuris are made for abuse and this guy is doing his job, though I have no idea about the story behind this one.
Mother's weight keeps the plank from falling, which is above a trap, either a hole or a water container. Food is used to move the mother from the center of the plank, breaking its balance and provoking its fall, taking the Koyukkuri with it.
I don't get how that works with the piece of glass though. Wouldn't the glass just... tip over or flip over and shatter with the board if mother reimu moves off it?