1997 Japanese model Tamagotchi. Gen 1, I'm pretty sure.

Some details on item's history:

Original seller I purchased this from had informed me that he had replaced the battery at one point and then replaced the battery pull tab.

The package is not sealed, the back cardboard piece slides on and off the back of the plastic package. Operation was confirmed when original owner replaced battery.

The unit itself appears to be in very good condition but the cardboard has some imperfections and wear as shown.