Motoko Shimada fondly recalls when a classmate at her public school in the city of Nara, Sanae Takaichi, showed early signs of the leadership that would set her on course to become the country's first female prime minister.

It was just before an important high school entrance exam, and Shimada had forgotten her lunch, intensifying already jangling nerves.

"Let's share mine," a young Takaichi gestured. Another classmate, overhearing the offer, also came forward. "Thanks to that, I passed the high school entrance exam. I’m truly grateful," recalled Shimada.