Concern continues to grow over the fate of Kenji Goto since the passing of a deadline by which a group believed to be the Islamic State of Iraq and the Levant (ISIL) threatened to kill him.
A journalist with substantial experience in conflict zones, Goto, 47, is known for his composure on the job.
To those who know him well, Goto's venture into Syria last October seemed hasty, as if he had been willing to enter the ISIL-controlled area regardless of the risk.
Was there something behind this dangerous move?
'He seemed resolved'
"He used to talk about the line between danger [and safety]," Kazunori Kurimoto, a video director who is friends with Goto, told The Yomiuri Shimbun.
Kurimoto, 53, has known Goto personally and professionally since 2004. They last spoke on Oct 24, right before Goto entered Syria.
During a video call over the Internet, they spent an hour discussing a project they were working on together. Kurimoto said Goto seemed normal and made no mention of Syria.
But the next day he received an e-mail from his friend, saying: "I actually just entered Syria. I couldn't bring myself to tell you yesterday. I'm sorry."
Goto was captured soon after. "It's like he was determined to do something," Kurimoto said.
Worries about Yukawa
Kurimoto said he heard Goto was concerned about the safety of Haruna Yukawa, 42, who was also captured by the militant group.
Goto had taught Yukawa, who had little experience in conflict zones, how to avoid danger.
"He hasn't harmed anyone. He deserves to come home alive," Goto was quoted as saying of Yukawa.
Goto is thought to have headed toward Raqqa, an ISIL stronghold, to rescue Yukawa.
"If he believed there was any chance he could save [Yukawa], he would never just let it be. His unswerving character may have ended up causing trouble for him," Kurimoto said.
Goto's movements indicate he acted hurriedly.
On Oct 23, Goto was in Gaziantep, southern Turkey, where he enlisted Syrian guide Alaaeddin Al-Zaeem to accompany him across the border. The next day, the pair crossed a border in the city of Kilis into Syria.
On Oct 25, Zaeem shot a video of Goto in the city of Marea.
In it, Goto said, "Now I'm gonna go to [Raqqa]...Whatever happens to me … all responsibility is on me."
Zaeem urged Goto not to go to Raqqa, calling it "crazy." But Goto was apparently determined to go, and set off after asking a different guide to accompany him.
Before leaving Japan, Goto e-mailed a friend, saying he would return home on the morning of Oct 29.
If that was indeed his plan, he would have needed to board a plane back to Japan on the night of Oct 28, which would allow him only three or four days in Syria.
"If something happens, it can easily hold you up," Junpei Yasuda, a journalist who knows Goto well.
"You'd expect him to give himself more time to report in a danger zone."
"Maybe he received some highly reliable information on Yukawa," Yasuda said.
Another of Goto's colleagues in the profession, Toshitsugu Maeda, remembers Goto returning from trips into Syria after about half a day on Oct 2 and 3.
He said Goto told him he returned because "things around the border are as tense as they've ever been. It's too dangerous."
Such clues make it all the more mysterious why Goto apparently insisted on crossing the border later that month.
"No matter what happens, I hope he makes it back alive," Maeda said.