Glorious Day follows the life of Han Song-jung, a single mother and writer who is determined to find successful and stable marriages for her three distinct daughters. As she navigates the complexities of modern relationships, she moves her family into a new home, leading to unexpected encounters with the neighbors, the Seo family. The series explores the generational differences in love and marriage, highlighting the challenges of blending two families with different values and backgrounds. As the story unfolds, the eldest daughter, Da-in, finds herself in a complicated romance that tests her personal growth, while the middle daughter, Da-jung, experiences a transformative journey of self-discovery. The drama balances lighthearted comedic moments with poignant emotional beats, ultimately focusing on the importance of family bonds, forgiveness, and the pursuit of genuine happiness in the face of societal expectations.