On 21st August 2021 at 8:45 p.m. an amateur named Sakai-san (call sign unknown) was at the Mt. Chokai hiking trailhead (1,000M elevation) in Yamagata Prefecture making QSO's when he heard someone calling SOS on his frequency.

Turns out it was a small boat that was being moved from Hokkaido to Okinawa which completely lost power (including the marine radio) off the coast of Niigata Prefecture. One of the guys had an amateur handheld but was unable to contact the coast guard directly as the coast guard in Niigata does not have an amateur radio monitoring station set up and no phone signal was available.

Sakai-san confirmed their location and situation and as he did not have a mobile phone signal he relayed the information through another Amateur radio operator who then contacted the Niigata Coast Guard.

Sakai-san continued to talk to the guys on the boat, relaying messages and reassuring them until the coast guard arrived around 2:30 a.m. They were approximately 55km from shore.

More information - https://kahoku.news/articles/20210906khn000028.html