It is an unlikely friendship that ties the fates of war correspondent Kenji Goto and troubled loner Haruna Yukawa, the two Japanese hostages for which Islamic State militants demanded a $200 million ransom this week.

Mr Yukawa was captured in August outside Aleppo. Mr Goto, who had returned to Syria in late October to try to help his friend, had been missing since then.

For Mr Yukawa, who dreamed of becoming a military contractor, travelling to Syria had been part of an effort to turn his life around after going bankrupt, losing his wife to cancer and attempting suicide, according to associates and his own accounts.

A unit at Japan's Ministry of Foreign Affairs had been seeking information on him since August, people involved in that effort said.

Mr Goto's disappearance had not been reported until Tuesday's video apparently showing him and Mr Yukawa kneeling in orange t-shirts next to a masked IS militant wielding a knife.

Mr Yukawa first met Mr Goto in Syria in April and asked him to take him to Iraq. He wanted to know how to operate in a conflict zone. They went together in June.

"He was hapless and didn't know what he was doing. He needed someone with experience to help him," Mr Goto told Reuters.

Mr Yukawa then returned to Syria in July on his own. Mr Goto, 47, returned to Japan.

Mr Yukawa's subsequent abduction haunted Mr Goto, who felt he had to do something to help the man, a few years his junior.

"I need to go there at least once and see my fixers and ask them what the current situation is. I need to talk to them face-to-face. I think that's necessary," Mr Goto told Reuters in August, referring to locals who work freelance for foreign correspondents, setting up meetings and helping with the language.

Mr Goto began working as a full-time war correspondent in 1996 and had established a reputation as a careful and reliable operator for Japanese broadcasters, including NHK.

"He understood what he had to do and he was cautious," said Naomi Toyoda, who reported with him from Jordan in the 1990s.

Mr Goto, who converted to Christianity in 1997, also spoke of his faith in the context of his job.

"I have seen horrible places and have risked my life, but I know that somehow God will always save me," he said in a May article for the Japanese publication Christian Today.

But he told the same publication that he never risked anything dangerous, citing a passage in the Bible, "Do not put the Lord your God to the test".

In October, Mr Goto's wife had a baby, the couple's second child. He has an older daughter from a previous marriage, people who know the family said.

Around the same time, he made plans to leave for Syria and uploaded several short video clips to his Twitter feed, one showing him with media credentials issued by anti-government rebels in Aleppo.

On 22 October, he emailed an acquaintance, a school teacher, to say he planned to be back in Japan at the end of the month.

Friends say he travelled from Tokyo to Istanbul and travelled from there to Syria, sending a message on 25 October that he had crossed the border and was safe.

"Whatever happens, this is my responsibility," Mr Goto said on a video recorded shortly before he set out for Raqqa, the capital of what IS calls its caliphate.

That was the last time he was seen before the IS video this week.