He learned that soon-to-be kamikaze pilots trained with that type of rifle.
Hawkins, along with the help of a friend, found a museum for it in Kanoya, Japan.
"About half of all the Kamikaze missions launched against the U.S. Fleet flew from Kanoya," said Hawkins.
"Somebody had this at a garage sale in Kailua," said Fort DeRussy Army Museum historian Sheldon Tyau, who was pointing to a rare bomber site in a glass case.
He said the war artifacts and collector's items are the reason so many people visit Hawaii's Fort DeRussy museum.
"The Pacific battles were some of the fiercest that were fought. These were kids that were 17, 18, 19 years old," he said.
The rifle was only here briefly at Fort DeRussy museum, but it was the perfect place for a handing over ceremony.
The halls are filled with memorabilia from past wars and from the people who served in them.
"I was moved to send it back to Japan because it represents the courage of their soldiers. It didn't take long to figure out it's the right thing to do," said Kaulukukui.