When Shuichi was a child, his best friend was a carefree boy named Yuu who loved exploring, roughhousing, and video games. Ten years later, Shuichi is stunned to discover that Yuu is actually Yuika, a beautiful young woman. Before he can even process the surprise, their families arrange for them to marry, and the two suddenly find themselves living together as husband and wife. Shuichi and Yuika are high school students navigating the awkward transition from childhood friends to newlyweds. They share a deep bond from their shared past, but the new dynamic of marriage brings a wave of unfamiliar shyness and mutual awareness. The story follows their daily life—attending school, spending time with friends, and growing accustomed to married life. Both are clearly attracted to each other but hesitate to take the next step, leading to a series of sweet and comedic misunderstandings. Their relationship is tested by outside forces, such as the return of Yuika’s strict grandmother, who demands that the young couple prove their commitment, and the arrival of Yuika’s younger sister, Kannon, who stirs up additional chaos. Through summer vacations, group trips, and a private honeymoon, Shuichi and Yuika gradually move beyond the comfort of friendship and finally push past the final barrier of uncertainty, culminating in a heartfelt confession and the true beginning of their romance as a married couple.