Puniru is a Kawaii Slime

Synopsis (en anglais)

Seven years ago, Kotarou made a slime that unexpectedly came to life. He named her Puniru, and they’ve been best friends ever since. The two have grown up a lot over the years, and Puniru is now a beautiful, carefree girl who can shapeshift into other cute forms. But with her spontaneous spirit and wild antics, Kotarou can never catch a break! (Source: Crunchyroll, edited)