If you're looking for manga similar to Hamster Ichibanboshi Densetsu, you might like these titles.
Chikomaru is a hamster who lives by himself in a home with thin-strawed tatami flooring. Chikomaru is unlucky, and prone to being confronted with rather unfortunate happenings... This is the tale of that hamster's slightly humorous, but slightly heartrending everyday life.
Death comes suddenly to a loved one. Though their body may have perished, you cling to the hope that their soul will stay with you. It is the year 2222, and that dream has been made a reality in a local city of Japan. Today, at the Soul Foundry in the center of the city, people's souls are being transferred to the bodies of others, or sometimes, to things that aren't human. This manga is a story about the curious, bittersweet love and human dramas that exist in an age where souls can remain in this world after death.