Aldi Novel Adilang, 19, was in charge of lighting the lamps on a fish trap that used light to attract fish, according to a Facebook post from the Indonesian consulate in Osaka, which oversaw Aldi's rescue.
Mr Aldi had been contracted to light lamps around the Rompong to attract and trap fish, and only had a walkie-talkie for company.
On Sept. 9, Aldi returned to his family in North Sulawesi, an Indonesian province whose islands form the eastern ring of the Celebes Sea.
"Aldi said he had been scared and often cried while adrift", Fajar Firdaus, a diplomat at the consulate in Osaka, told the Post. Each week, the owner would send someone to collect the fish and replenish supplies of food, fuel and drinking water.
The 19-year-old spent 49 days out at sea, catching fish and keeping himself hydrated by sipping seawater through his clothes to reduce his salt intake. He was picked up by the Panamanian vessel off the waters of Guam.
"After he ran out of the cooking gas, he burned the rompong's wooden fences to make a fire for cooking", said Mirza Nurhidayat, Indonesia's consul general in Osaka, Japan, who was quoted by The Jakarta Post.
During high winds on July 14, the worn rope tore and the teenager was pushed by the heavy winds out to sea.
When it did not rain for days, he said he "had to soak my clothes in the sea, then I squeezed and drank the water". "None of them stopped or saw [him]".
Just when things were looking bleak for him, on 31st August, Aldi spotted a nearby tanker and caught the captain's attention when he switched his radio to an emergency frequency.
After arriving at the Japanese port of Tokuyama on September 6, Aldi had to spend another night on the cargo vessel.
His mother, Net Kahiking, recalled the sheer terror she felt when she was told Aldi went missing.
Coast Guard Sector Guam confirms they received a call at the time of the rescue, but handed the information over to the Japan Coast Guard as the vessel that picked up the teen was heading towards Japan.
The post added that the consulate expressed its appreciation "to all parties involved in rescuing and returning Aldi home safely to Indonesia".
Aldi arrived in Japan on September 6 from where he was flown from back to Indonesia after consular officials verified his identity. "Japan after the ship moored and made sure that he was in good health", the statement said.