Lena, who was living with her family in a slum, suddenly recalls her memories of living in Japan. A clean house, delicious food, lots of entertainment... Comparing those comfortable days to now, I can't stand the current situation. Aiming for a rich life, Lena plans to work in the city... She shows off her special skill, mental arithmetic, at a market run by the people of the city and begins negotiating to get hired. Use your calculation skills as a weapon!! A Cinderella story in another world where you can find happiness begins!!