Nobuko Mitsumori, 37, works with her mother in their small accounting office in Tokyo's Chuo Ward. With one assistant and myriad clients, the three are always happily overworked. Nobuko studied classical literature and didn't think that math was her strength, but thanks to her talent, the numbers somehow always add up.

My mom always says that for a woman to succeed, she has to work three times harder and be three times better than a man. I don't believe that. Maybe in her time it was like that but now it is so much easier: twice as hard is just about right.

I have a serious occupational disease: I can not stop adding things up. When I go to a restaurant, I immediately count the chairs, the employees and figure out the rent, utilities, etc. Then I look at the menu and I keep adding, subtracting, multiplying, dividing and the work keeps going on in my head. I get no rest from numbers.