A story in which young people who share a world of their own become each other's confidants and the light that illuminates their lives. Yeon Tae Seo is a subway driver with a sharp perspective on the world. Tae Seo is an independent person who lives faithfully to the present, focusing on "just today" rather than the future or dreams. While successfully achieving his longed-for independence and settling down, he encounters Mo Eun A, his first love from when he was nineteen, which gently stirs up ripples in his daily life. Mo Eun A is a former hotelier turned Seoul lodging manager brimming with passion, depth, and lovable charm. Setting goals for herself—where, with whom, what, and how—she experiences small triumphs and major setbacks until she reunites with her first love, Yeon Tae Seo.