A Long Island tourist arrested in Japan as he transported the severed head of a woman in his suitcase was a coddled “mama’s boy” who served briefly in the US Air Force, The Post has learned.

Yevgeniy Vasilievich Bayraktar, 26, was on vacation when authorities busted him leaving his Osaka rental with the grisly remains of a Japanese woman he had met on a dating site last month.

Little is known about Bayraktar, who lived in a modest bungalow in Mastic Beach with his mother and her third husband.

He was briefly stationed at the McConnell Air Force Base in Kansas before he was “separated” from the service in June 2012, serving only 11 months of a four-year stint as an airman first class, an Air Force spokesman told The Post.

He refused to say why Bayraktar was prematurely discharged.

Bayraktar was born in Odessa, Russia, and arrived in the US as a 9-year-old after his mother married a Texas engineer she met on a dating site.

“He and his mother were very close, but he and I were not,” said Benny Dacy, Bayraktar’s former stepfather, who now lives in Houston.

Dacy traveled to Odessa to meet his future bride, who was 12 years his junior and trained as an engineer. She lived with her only son in a cramped one-bedroom apartment, Dacy told The Post.

Dacy flew them to the US where he married Regina in a civil ceremony at the city hall in Abilene, Texas, where he then had a home.

Dacy said he tried to cultivate a relationship with the boy, but he kept to himself and was very close to his mother.

“He was a mama’s boy,” said Dacy. “If we were having dinner and he didn’t like the food, his mother would get up in the middle of the meal to cook him something special, and this was at a time when we didn’t have a lot of money.”

Dacy, 69, told The Post that Bayraktar, who was known as “Jake” when he lived in Texas, maintained contact with his biological father, a doctor who sometimes sent him money from Russia.

After Dacy financed Regina’s nursing-school studies in Texas, she and her son simply disappeared, he said.

“She called once to ask me for a divorce but I had no idea where they were until the news hit,” Dacy said. “It was the most traumatic time of my life when she just left me. She is a very selfish woman.”

Regina, who is married to another engineer, works as a registered nurse at a rehab facility in the Hamptons, according to a LinkedIn profile which was taken down last week.

Bayraktar was arrested Feb. 22 on suspicion of killing and dismembering Saki Kondo, 27, who was reported missing by her family on Feb. 16, a day after she went on a date with Bayraktar.

Police said that Bayraktar, who had been traveling in Japan since January, met the victim on an online dating site and took her to a vacation home he rented in Osaka, where he allegedly dismembered her between Feb. 16 and Feb. 18. He was on his way to another apartment he rented when police arrested him with Kondo’s severed head in his baggage, according to Japanese authorities.

Last week Bayraktar led police to the remaining body parts he allegedly buried in a forest on the outskirts of Osaka and Kyoto.