Yotsuba Koiwai is the main protagonist of the manga series "Yotsuba to!" written by Kiyohiko Azuma. She is a curious and adventurous five-year-old girl with a cheerful personality and a unique perspective on the world around her. Yotsuba lives with her adoptive father, Koiwai, and her daily life is filled with new experiences and discoveries. Her childlike innocence and boundless enthusiasm often lead to humorous interactions with her neighbors and friends. The series focuses on her everyday adventures and the joy she finds in simple things, capturing the essence of childhood wonder.