Another kind of "Mishter Threasure" loved by Koyukkuris are small bouncy ball that allow them to exercise and play with. On a much deeper level of sophistication there are yukkuri Dolls, reproductions of koyukkuris of every species known. When faced with a koyukkuri doll, a koyukkuri will act much like a human child with her new doll, playing "myamya" or "big shishter" to it, munching some food in front of the doll and pretending it's eating, keeping it clean and endlessly chatting with it. Especially really young koyukkuris will act with their dolls with no difference from the way they would act to a living koyukkuri, even identifying the doll as the real article. As such, koyukkuri dolls are sought after by people able to afford and care for a single koyukkuri only, as they prevent the onset of depression and anti-yukkuritis that comes with loneliness.
Koyukkuri dolls may range from simple, painted reproduction of koyukkuri, often made of soft plastic and eraser gum, to more advanced plush dolls with recorded, pre-set phrases (such as "Chake id eajy!" and "Wet's do wub wub!").
Adult Yukkuri
While not commonly seen, adult yukkuri have been seen playing with "Mister Treasures". While not known why some adult yukkuri retain this behavior, it has been guessed that it could be a way for a "richer" yukkuri to show off to others. Another theory is that if a yukkuri does not develop properly during its youth it will, rather then be around other yukkuri, contain itself with inanimate objects.