If the recent surge in tourism has you standing on the ledge, blame the Japanese. It’s a culture known for elaborate gift-giving ceremonies, but it seems that in at least one instance, they weren’t so good at receiving.

In 1909 and 1910, the mayor of Tokyo thought it a nice gesture to ship a few thousand cherry trees to Washington—a gift that the Americans have venerated and placed in the arboreal pantheon along with California’s redwoods and Florida’s palms.

The humble white dogwood (Cornus florida) familiar to us in North America—which now dots Tokyo’s ultramodern landscape—was sent to Japan in 1915 as a reciprocal token of friendship. But in Japan, no one seems to care about the dogwood. Let’s face it, it was like giving a Swiss man a box of Russell Stover. The dogwood-for-cherry-trees trade doesn’t have anything on arms-for-hostages.

In an overzealous attempt to make amends for his seemingly ungrateful countrymen, independent Japanese filmmaker Noriyuki Amemiya spent two years documenting ceramic artist Yoshihiko Mene’s honorable but superfluous quest to find the original American dogwoods planted in Tokyo 85 years ago.

“At first, I tried to find the original dogwoods myself,” says Amemiya, “but I decided to shoot [Mene] because he had devoted a considerable amount of time to the search.”

Amemiya, 36, a print and broadcast journalist in Japan, graduated from the film program at American University in 1998. “Every spring, I would go visit the sakura at the Tidal Basin,” he says. Like most visitors, though, Amemiya was not aware of the reciprocal arrangement. When he did find out about the dogwoods, he wondered why the story wasn’t widely known. “It is embarrassing for the Japanese people,” he says.

His 30-minute film, Hanamizuki (Dogwood Trees): A Goodwill Ambassador Passed Into Oblivion, with its Muzak-like soundtrack, follows Mene through various Tokyo parks, agricultural laboratories, and private gardens. With a measuring tape clipped to his belt, Mene measures the circumference of every dogwood in sight in the hope of finding one thick enough to be an original.

All this, of course, makes for anxiety-driven viewing. Like the classic BBC series A Man and His Dog—in each episode of which a man and his dog must herd hundreds of sheep across a pasture into a distant pen—the film keeps you gripped. You always wonder what will happen if Mene can’t deliver the goods and produce an original. Not to give away the ending, but let’s say the matter is brought to satisfying closure.

“This story is about two countries’ friendship,” Amemiya says. “It is an untold story that must be told.”—Guy Raz

For more information on Hanamizuki, including how you can see it, contact Mamoru Ninomiya, (703) 356-2294.