ねずみくん is a popular character from a series of children's books created by Japanese author なかえよしを and illustrator 上野紀子. The character is a small, cheerful mouse who embarks on various adventures with his friends. The stories often emphasize themes of friendship, kindness, and problem-solving. The illustrations in the ねずみくん series are colorful and engaging, making them appealing to young readers. Each book typically features simple language and relatable situations, helping children develop their reading skills while enjoying the adventures of ねずみくん and his companions.