Bold and witty Nanoka Koyanagi believes she is above the typical assignments that her teacher gives in school. Rather than participating in her physical education class, the young girl crafts a foolproof argument to avoid any activity altogether. Instead of being impressed, Nanoka's worried teacher decides to give her a new task—to find the meaning of the word "happiness."

As Nanoka mulls over the answer to such a difficult question, she seeks advice from two of her closest friends: Obaa-chan, an elderly woman living in the woods; and Abazure-san, a young woman living alone in a nearby apartment. Along the way, Nanoka befriends high school student Minami at an abandoned building, whom she initially met while Minami was hurting herself. Each of them has a different outlook on life, making Nanoka's mission to figure out what it means to be happy even more challenging.

During her search, it seems that there is something bigger drawing Nanoka to these three women. The more she investigates, the closer she gets to her friends and learning about herself.

Mata, Onaji Yume wo Miteita was published digitally in English as I Had That Same Dream Again by Seven Seas Entertainment on March 12, 2020, and in print on July 7, 2020. Seven Seas Entertainment's publication was nominated for the Eisner Award for Best U.S Edition of International Material—Asia in 2021.