This is a series of gashapon (capsule toys) or trading figures depicting characters or people.
From Good Smile Company:
Illustrations from the popular "irasutoya Party" stamp set have been turned into adorable keychains! The line-up includes Rabbit, Dog, Cat, Bear and mukimuki Cat for a total of 5 keychains! Be sure to add them to your collection!
One box of this item contains a complete set of the possible types.