Maruko and her friends pick up a stray puppy. She begs her mother to let them keep it, but her plea is dismissed as just another one of “Maruko’s passing whims.” With no other choice, she asks around in class the next day for someone to adopt it, and class rep Maruo suggests the whole class raise it together.
まる子は友達と子犬を拾った。家で飼いたいとお母さんにお願いするが、”まる子の気まぐれ”と許してもらえない。しかたなく、翌日のクラス会で飼い主を募ると、委員の丸尾くんがクラスで育てようと提案する。