Somewhere between downtown Utsunomiya in Tochigi Prefecture, and the village of Ogisu an hour's drive to the northeast, Dr. Tatsuhiro Ohkubo pulls over to buy a box of sakura mochi.
Back on the road, he passes one of the bright-pink rice cakes to the back seat for Dr. Sergiy Zibtsev, who is visiting Japan for the first time. His tall frame folded grasshopper-fashion into the small car, the Ukrainian forest ecologist bites into the salted cherry leaf wrapped around the rice cake.
"Mm," he says. "What species is this?"