Mami Tsumura is a Japanese manga artist best known as the creator of the series Kotaro Lives Alone. She wrote and illustrated this work, which was serialized in Shogakukan's seinen manga magazine Big Comic Superior. The series began its run on March 13, 2015, and concluded on June 9, 2023. Its chapters were collected into ten tankōbon volumes, with the first released on December 28, 2015, and the final volume published on August 30, 2023.

Kotaro Lives Alone is Tsumura's most prominent work and centers on a four-year-old boy named Kotaro Sato who lives by himself in a modest apartment complex. The story follows his daily life and his relationships with his adult neighbors, including a struggling manga artist, a hostess, and a man often mistaken for a yakuza. The series is known for blending comedy with poignant themes, exploring child independence, neglect, and the formation of unconventional family units. Critics have described Tsumura's approach as a bittersweet comedy that addresses dark aspects of Japanese society with tenderness and avoids excessive melodrama.

The commercial and critical success of the manga led to multiple adaptations. In 2018, the series won the Electronic Manga Award in the Boys' Category. A ten-episode live-action television drama was produced and broadcast on TV Asahi from April 24 to June 26, 2021. Following this, an original net animation adaptation was produced by Liden Films. The anime series, directed by Tomoe Makino, premiered worldwide on Netflix on March 10, 2022. As of June 2022, the manga had over 1.7 million copies in circulation. Beyond the creation of Kotaro Lives Alone, no other original manga works by Mami Tsumura are documented in available records.