TOKUSHIMA -- "Here it comes from that valley. There it is. Isn't that low? Wow!" With a woman's exclamation, a fighter jet roars into view over mountain ridges, delivering an ear-splitting blast and in seconds it is gone. A young boy, startled by the loud sound, bursts into tears.

These scenes were captured on video from a house nestled in the mountains of the Monobecho district of the Kochi Prefecture city of Kami in December 2014, and the video has since been viewed some 6.3 million times on YouTube. The home is located right under the "Orange Route," a training path for low-altitude flights by U.S. military aircraft.

Previously, it was difficult for those who had never encountered low-altitude flight training by U.S. military aircraft to imagine what it was like. However, this "shocking" video has led to a surge in similar videos being posted on YouTube and other platforms. What made this possible was the emergence of the free messaging app Line, which has some 97 million users in Japan.

The woman in her 50s who filmed the video was frequently troubled by the roar of U.S. military aircraft flying over her home, and her anxiety was heightened by never knowing when and from which direction the planes would come.

Around this time, she learned that some residents living under the Orange Route were sharing flight information by phone. "I want to be informed by phone too," she thought. The flight path of the U.S. planes was known and if residents had information on sightings in other areas, they could predict how many minutes it would take for the aircraft to pass overhead. However, with jets flying at supersonic speeds, covering over 10 kilometers in a minute, one-on-one phone calls were far from quick enough.

That's when she thought of utilizing the Line app on her smartphone. She created a Line group, and had people interested in low-altitude flights by U.S. military aircraft join.

When members witnessed low-altitude flights or heard the aircraft noise, they would post the information on Line, instantly informing the entire group. Some members would activate their smartphones' video modes or attach telephoto lenses to their cameras and face the direction from which the aircraft were due to approach, enabling them to capture clear videos and photos. Currently, about 40 people from areas under the route, including those in Wakayama and Tokushima prefectures, participate in the group.

The Orange Route extends from Ehime, Kochi and Tokushima prefectures across the Kii Channel to Wakayama Prefecture. Masafumi Fujimoto, a member of the Mugi town assembly in Tokushima Prefecture, has been documenting U.S. military low-altitude flights for over a decade. He says westward-bound aircraft reach southern Tokushima Prefecture about five minutes after members in Wakayama post information about them, making it easier to attempt capturing footage of them.

Today, searching keywords like "low-altitude flight" and "U.S. military aircraft" in Japanese on YouTube yields numerous videos capturing these low-altitude flights.

The woman commented, "When U.S. military aircraft fly low, it's enough to make babies cry and dogs panic. If people (outside the route) see the videos, they'll probably get a feel for the severity of the situation, such as the loud noise."

The woman has since moved to a place without low-altitude flights, and her thought every day is, "Ah, peace."

"It's important for everyone to watch the sky and document these flights. I hope similar groups form in other regions with U.S. military flight routes, like in the Chugoku region," she said.

The repeated low-altitude training flights and past accidents along the Orange Route continue to raise important questions about their impact on local communities and the broader implications for Japan-U.S. security cooperation.

(Japanese original by Koichi Uematsu, Tokushima Bureau)