She writes the recipes, changing them to reflect seasonal ingredients, and she's realized, over the years, that kids will eat almost anything if you serve it to them right. They'll eat hijiki, an earthy black seaweed, if you mix it with rice. They'll eat small whole fish, heads and all, if they are lightly fried. Tofu is an easier bet, but just to be sure, it sometimes comes with minced pork.
Fujii doesn't teach a class, but three or four times a year, classrooms come visit her for lunch - meaning they eat in the cafeteria, rather than their classrooms. This field trip comes with a small price: After the kids have served themselves the food, but before they can eat, they get a five-minute lecture about the items on their plates.
Lunchtime, on this particular day, begins with a call from the teacher in the cafeteria.
"People in charge, please come up."
Six third-graders put on their white sanitary smocks and caps and take their positions behind serving trays. One child eyes the thick reservoir of Sichuan tofu and wiggles his right arm, as if to warm up his ladling hand. A teacher shows the girl serving rice how much to give each of her classmates - between 160 and 180 grams.
"Is this okay?" the girl asks as the first student comes by.
When everybody sits back down, the lecture begins.
"Today's meal is made up of various ingredients, but to fill you up, you have to eat everything fully," Fujii told the class of third-graders. "If you finish this whole lunch, it means you are taking in 21 ingredients."
One child interrupted.
"You have to eat a balanced meal."
"That's right," Fujii said. "You can get full without vegetables, but we still need them. Why do we need them? Because they have Vitamin C, which makes you stronger."
Japanese food, contrary to the common perception, isn't automatically healthy; it includes crispy chicken, rich bowls of salty ramen with pork belly and battered and deep-fried tempura. But, like most cuisines, it can be healthy.
Japan began emphasizing healthy food for its students in the aftermath of World War II, when the government prioritized education and health as a way to catch up to the modernized West. For a decade after the war, school lunch food was still coming from international donations. Many older Japanese remember postwar school meals of powdered skim milk, bread and daikon radish. But by the 1970s, the school meal came to look much like the modern-day standard. These days, ethnic food (such as Korean or Italian) is mixed in once or twice per week.
Japanese government officials say no other country has copied Japan's system of made-from-scratch meals eaten in classrooms, or even tried to.
"What is most difficult for me to explain is why we can do this and other countries cannot," said Masahiro Oji, a government director of school health education at the Education Ministry.
Oji mentioned that last year he attended an Asia-Pacific Economic Cooperation workshop in Moscow on school lunch programs. Japan sent members of its education ministry, Oji said. Most other nations sent members from their agriculture or farm ministries.
"Japan's standpoint is that school lunches are a part of education," Oji said, "not a break from it.