If you're looking for anime similar to Koro's Big Day Out, you might like these titles.
Just before dawn, Boro the Caterpillar hatched from an egg among patches of scrub grass. Looking around for the first time in fascination, he noticed the brilliance of the morning sun and a deliciousness in the air. As the sun lights up the grove, the borogiku (groundsel) leaves began to photosynthesize. "The air and water taste great!" Boro stepped out into the world of caterpillars' friends and foes.
This story follows the daily lives of a cat named Tama and his cat and dog friends. As their curiosity gets the best of them, they learn enduring values of friendship and teamwork.
A boy named Yuji and his friend Gick, a rabbit, find a walking stick. To decide which of them will keep it, they try a foot race, a long jump and sumo wrestling, but each ends up in a tie. Out of ideas, the children go to Gick's Granny for help. Granny tells the children to go treasure hunting. Who will be the winner?
A puppy, Poko, jumps out of a refrigerator and takes a boy, Misuke, to an ice world full of adventure through the refrigerator. In the ice world, there is a girl called Nally who wants warm food. So they try to find some warm food for her, but everything freezes so quickly in the ice world...