The autobiographically inspired, moving, and real story of a Korean diaspora railway engineer who took root in Japan, whose real name is `Kawauchi Ramo`!! Young-mi (Jeon Ju-yeon), a single mother working at a trading company, always harbored the desire to put an end to three generations of poverty. Meanwhile, upon seeing a newspaper article stating that the value of the Japanese yen is four times the value of the Korean won, she painstakingly creates an opportunity to enter Japan. With the determination and courage that her children must not have to quit school due to tuition fees, she carves out the international market on her own. In the ruthless business world, Young-mi works diligently with a strong spirit that action precedes words, but she is always kind to her Korean mother (Jeon Won-ju) and siblings. After many twists and turns, Mr. Fujita (Dokgo Young-jae), a Japanese man who always helps the desperate Young-mi, who hastily brought her children to Japan, is a great blessing. Returning to Korea, Young-mi acquires advanced railway technology in Japan and participates in projects as a high-level engineer. When she decides to transfer her technology to her homeland, external pressures quickly arrive. The stakeholders, who want a quick opening at the expense of safety, clash with Young-mi, bringing her a great ordeal…