This story is about a boy named Nagatoro Yuuki, whose parents divorced when he was in elementary school due to differences in their parenting styles. His mother, who wanted to raise him freely, clashed with his strict father, and Yuuki would often seek refuge at his aunt's house whenever arguments escalated.
After the divorce, Yuuki's father remarried, causing confusion for Yuuki as he adjusted to his new life. Meanwhile, three moms who were already friends decided to start a group called "Yuuki's Mama Mutual Support Club" aka "Mama Club" to protect and raise Yuuki.
One day, Hiroki was caught masturbating by his new mother, leading to a discussion on proper sexual education within Mama Club. This sparked a competition for Hiroki's affections, involving his friends, a teacher and a tsundere classmate, resulting in chaos.

[Condensed from DLsite]