This Game Boy Color game, part of the Nakayoshi Pet Series, lets players care for a virtual puppy. The gameplay probably involves familiar tasks such as feeding, playing with, and training the puppy.  The game is likely targeted towards younger players and provides a simple virtual pet simulation.  Information regarding the specific gameplay details and developer is limited.

Nakayoshi Pet Series 3 - Kawaii Koinu (Japan)

Nakayoshi Cooking Series 5 - Cake o Tsukurou (Japan)