However, despite their playful, joyful and childish disposition, their extreme similarities to a koyukkuri and their small size, mini-yukkuri are still able to reach maturity. As such, an inexperienced owner will be dismayed at discovering a Mini-Yu showing signs of psychical maturity, such as an increased drive for nesting, breeding and form its own (albeit smaller due to its inability to breed in large numbers as fast as a regular size yukkuri) family. As such every precaution taken for normal sized Pet, from sterilization to a strict education, is needed even for the cuter looking Mini-Yus. Otherwise, the owner could still allow them to nest; despite their physical limitations, mini-yukkuris can still be fine parents and addressing their needs for increased food intake and new, soft materials for the small koyukkuris to fall after detaching their pregnancies will be as safe as the ones of regular sized Yukkuris.
When purchasing a mini-yukkuri, caution is to be taken as some sellers may try to sell a koyukkuri as a "full-grown mini-yukkuri". While the major tell-tale sign is the mini-yukkuri becoming larger, the yukkuri can be easily tested by asking where its parents are. While koyukkuri will generally begin to cry when they notice their parents aren't around, "mini-yukkuri" will generally not seem to mind. Other signs are the yukkuri's obsession to "wub-wub" and excrement attached to the body (as koyukkuri are still unable to clean themselves).