Kokoro Yotsuba is a fifth-grader who lives on the seaside town of Aozora, who is clumsy yet also takes good care of her belongings. Living alongside her brother, she once understood what her grandmother said to her, regarding that "everything has a soul" and that things should be cherished. One day, a strange egg was born from her colored pencil she cherished the most, revealing to as Luckytama, a Cocotama.