TOKYO - Militants from the Islamic State in Iraq and Syria (ISIS) group released a video on Tuesday purporting to show two Japanese men they were holding. Wire agency AFP reported that a masked jihadist demanded a US$200 million (S$270 million) ransom for their release.

Here are brief profiles of the two men who know each other.

Mr Haruna Yukawa is a 42-year-old widower who reportedly has a history of attempted suicide and self-mutilation.

Mr Yukawa opened a military goods shop in Chiba, outside Tokyo, after leaving high school, according to a website affiliated with the popular Sankei newspaper.

He married in 2000, but his business soon went bankrupt and his wife later died of cancer, the website has said.

Citing his father, the website said a devastated Yukawa changed his original name - Masayuki - to Haruna, usually a woman's name, in the belief that the Chinese characters used would herald a shorter life.

The website said he had tried to kill himself and had cut off his own genitals.

Reuters reported in August that Mr Yukawa had been forced to live in a public park for almost a month at one point. The news agency also claimed he borrowed money to travel to Syria and dreamed of providing security to big Japanese companies in conflict areas like the coast of Somalia.

Mr Yukawa came to widespread attention in Japan when footage of his apparent interrogation in the Syrian scrub was posted online last August.

He was seen lying on the ground, with matted brown hair and wearing a black T-shirt stained by dust and sweat, as blood trickled down his face.

Mr Yukawa offered brief responses to questions posed in English about why he was in Syria and the reason he was carrying a gun.

He replied in stilted English that he was a "photographer" and a "journalist, half doctor", as his interrogators accused him of lying, with one placing a long knife near his chest.

"I'm no soldier," he said.

Another video surfaced showing a man believed to be Yukawa test-firing an AK-47 assault rifle in Syria.

The same video could also be seen at the website of Tokyo-based private military firm PMC, which lists Mr Yukawa as its chief executive. Pictures on the website show him with right-wing Japanese activists.

Its website said the firm has branch offices in "Syria, Turkey, Iraq, Africa", and it says its services include providing "security abroad".

Reuters said that Mr Yukawa first met Mr Kenji Goto, the other hostage, in Syria in April last year and asked to be taken to Iraq. Mr Yukawa wanted to know how to operate in a conflict zone. They went together in June. Mr Yukawa then returned to Syria in July on his own. Mr Goto, 47, returned to Japan. Mr Yukawa's subsequent abduction haunted Goto, who felt he had to do something to help the man, a few years his junior.

Mr Goto is a freelance journalist who established a video production company, named Independent Press, in Tokyo in 1996, supplying documentaries on the Middle East and other regions to Japanese television networks, including public broadcaster NHK.

Mr Goto has apparently been out of contact since late October after telling family that he intended to return to Japan, NHK reported.

In early November, his wife received email demands for about one billion yen in ransom from a person claiming to be an Islamic State group member, Fuji TV said.

The emailed threats were later confirmed to have come from a sender implicated in the killing of US journalist James Foley, Fuji TV said.

The Japanese government is believed to have discreetly started investigations after the threats contained information that only Mr Goto himself would know, the broadcaster said.

Mr Goto was born in Sendai, Miyagi, in 1967, according to the company's website.

According to heavy.com, Mr Goto contacted the Iraqi Journalists' Rights' Defense Association on Facebook on July 1 2014. In it, he introduced himself as a Japanese journalist, and asked for help in obtaining a visa to Baghdad, which he said he understood he would need a sponsor for.

The Independent said that Mr Goto, who has written books on AIDS and reported from conflict zones in Afghanistan, Somalia and other areas, was also filmed discussing his time in Syria at a UNICEF conference in March last year.