"I really wish we'd skipped the prolonged agony and started with hanging out, but whatever."
Just working in that hellhole already counted as a human rights violation, but Lomax was legit tortured, and for the dumbest of reasons. He pissed off Japanese authorities by MacGyvering a radio receiver out of scraps. Convinced that he was masterminding a POW uprising (or possibly starting a jazz club), officials spent a year trying to finesse a confession out of him. In the process, they broke Lomax's arms and hip, and forced water down his throat. There to help facilitate these enhanced interrogations was Nagase, an interpreter, who quickly rose to the top of Lomax's s**t list due to his cruel psychological taunts.
After the war, a traumatized Lomax helped hunt down his torturers, but Nagase was the one that got away. Lomax spent the next five decades dreaming of revenge and looking through war records to locate his old nemesis, but to no avail. Then, in 1993, he finally found Nagase, arranged a meeting (according to Lomax's wife, with every intention to kill him), and then ... they got along rather well, actually. It turned out they had a lot in common.
"I'm gonna murd-- hey, we're shirt twins!"
When he reunited with Lomax on the same bridge they'd both helped to build (one more than the other), a deeply shaken Nagase unleashed a torrent of tears and apologies. And he meant it. After the war, Nagase was plagued by guilt and helped the allies find mass graves along the railroad. From then on, he devoted his life to charity. Lomax and Nagase found that they were both haunted by the horrors of the past in similar ways. They even had the same pastimes, like writing, collecting documentation, and having horrible PTSD-induced nightmares. Fun stuff.