Having grown up in Japan with his Japanese mother, Yamamoto believed for nearly six decades that his American father had abandoned him.
The revelation came as a surprise, as he had suffered bullying during his childhood, with peers referring to him as "gaijin," meaning "foreigner," and telling him to "go back to your country."
Yamamoto's childhood memories were marred by loneliness and confusion as he lacked information about his father, knowing only that he was American.
"I had no way to search for him.
There were no clues, no information, nothing," he explained in an interview.
Over time, his relationship with his mother deteriorated, leading to estrangement for more than 30 years after she remarried and had another child.
On the other side of the Pacific Ocean in California, Sharon Lovell grew up in a nurturing home but witnessed her father, John Vieira, mourn the loss of a son he had left behind in Japan during the 1950s when he was stationed there as a soldier.
"I saw my dad cry so many times.
Most of the time, I knew it was because of that," said Lovell, now 71.
According to her, Vieira had fallen in love with a Japanese woman and they intended to marry; however, he was sent back to the United States before the child was born.
The woman informed him that the child had been put up for adoption and was a daughter.
Vieira searched for the child for years but never succeeded in finding her.
He passed away in 2003, unaware that he had a son, Akihiko Yamamoto.
In 2022, through a sequence of DNA tests on the genealogy platform MyHeritage, the connection was unveiled.
Yamamoto's daughter in Japan and Lovell's cousin in California each submitted their DNA.
When a genetic link was identified between the two, they began exploring their connection, ultimately discovering that Yamamoto is the missing son of John Vieira.