Maruko (Momoko Sakura) A girl who can be a bit lazy at times, but becomes incredibly curious whenever something interesting happens. She is kind and helpful, often reaching out to people in trouble and trying to solve problems with them. Because she rarely wants to do her homework or chores at home, she is frequently scolded by her mother. While she can be a bit of a slacker and a smooth talker, that's part of her bright and optimistic charm. She loves drawing, especially animals and plants.

Big Sister (Sakiko Sakura) Maruko's older sister. She has a serious and calm personality. She often gets exasperated or angry when Maruko is messy or tries to be sneaky, but they usually get along well. She is a reliable older sister who will listen seriously to Maruko's problems when she's in trouble. Her favorite food is eel, among others.

Dad (Hiroshi Sakura) Maruko's father. He has a carefree personality. He can be a bit scatterbrained and often half-listens to Maruko's stories or ignores her entirely. However, he is reliable in times of need. He loves alcohol, cigarettes, and watching baseball. He also goes fishing occasionally. His favorite foods are bonito sashimi and simmered fish.

Mom (Sumire Sakura) Maruko's mother. She often gets angry because Maruko doesn't listen to her, and she's always busy looking after everyone. She is a firm person and a great cook. Though she gets angry at Maruko, she is a warm-hearted person who will immediately and kindly forgive her if Maruko apologizes sincerely. Her hobby is embroidery. Her treasure is an opal ring. Her favorite foods are manju and yakisoba.

Grandpa (Tomozou Sakura) Maruko's grandfather. He has a kind personality and loves Maruko, Sakiko, and Guest so much that he can't help but spoil them. He's a bit absent-minded, so Maruko sometimes tries to get pocket money from him by sweet-talking him into it. He might get a little discouraged when that happens, but in the end, he always does everything he can for Maruko. That's how deep the bond between Maruko and Tomozou is. Also, when something happens, he sometimes secretly composes a haiku in his heart to express the situation. After reciting a haiku, he usually finishes with the words "Tomozou's Heartfelt Haiku." His favorite foods are yudofu, natto, and sea urchin.

Grandma (Kotake Sakura) Maruko's grandmother. She has a gentle and relaxed personality. While she usually has a laid-back atmosphere and just nods along, she occasionally drops a single, sharp remark that hits the nail on the head. She knows a lot of old-fashioned wisdom and sometimes teaches it to Maruko and the others. Her favorite foods are amanatto, Oiwake yokan, and sekihan (red bean rice).

Maruko's best friend. A girl characterized by her braids and glasses. She has a kind and serious personality, always taking Maruko's ideas and comments seriously. Sometimes, when something happens that is beyond her common sense, she has a romantic side where she secretly transforms into a girl of the Alps named "Tammy" in her mind to narrate her feelings. Her favorite foods are melon, pudding, cake, etc.