If you're looking for manga similar to Rilakkuma: Kagami no Naka no Korilakkuma, you might like these titles.
Tarepanda lives a happy and carefree life, but sometimes he needs to get out and go on a grand adventure. Rolling his way around the streets and down stairwells, Tarepanda finds himself in a variety of fun and interesting situations. Whether it's breaking bread with construction workers, lounging on a park bench, riding the train or becoming the subject of a painting, Tarepanda always manages to have a good time!
Chocopa is a baby panda that loves chocolate! He eats chocolate all the time. One day when he's eating his favorite chocolate, his white fur turned to chocolate color all the sudden. Now he looks more like a bear. But don't worry. Chocopa just needs to drink milk to get his white fur back, then he's a panda again!