An important artifact in Shugo Chara! that allows Hinamori Amu to character transform. It was left behind by the Founding King of the Guardians who wrote in his handbook that it is to be saved for the one person with three Guardian Characters.
It's counterpart is the Dumpty Key, which is held by Tsukiyomi Ikuto.
As it's name entails, the Humpty Lock resembles a lock with a keyhole in the center. It's typically worn as a necklace. Notably, it has four shapes resembling hearts or even petals that change color depending on the guardian chara Amu transformed with.
For characters from other series, this tag should only be used when this specific, canon design is featured. Do not use this tag for any unofficial designs for it.