"Wasn't there a GI who took like a thousand Japanese prisoners?"
I have no idea. See:
https://en.wikipedia.org/wiki/Japanese_prisoners_of_war_in_World_War_II
There was a guy who was American but was adopted and raised by Japanese family. He served in the Pacific and after seeing his friend get killed he went out and killed as many Japanese as he could, often by himself. Later he took a General and his whole division prisoners. ...by himself. It was something like that. Let me see if I can find the info
Here you go. Guy Gabaldon.
Japanese, they were ordered by their superiors on Saipan to kill seven American Marines or soldiers for every soldier they lost, or commit suicide
Gabaldon was reprimanded by his superior officers, and threatened with a court-martial for leaving his post. However, according to him the next night he went out and did it again. He carefully approached a cave, shot the enemy guards outside, moved off to one side of the cave, and yelled in Japanese, "You're surrounded and have no choice but to surrender. Come out, and you will not be killed! I assure you will be well-treated. We do not want to kill you!"
The next morning he says he returned with 50 Japanese prisoners. As a result, Gabaldon was permitted by his commanding officer to act as a "lone wolf" operator
July 8, Gabaldon captured two more enemy guards. He convinced one of them to return to his cave, with an offering of surrender. Shortly thereafter, a Japanese officer showed up. After speaking to Gabaldon, the officer accepted the conditions of surrender—and over eight hundred Japanese soldiers and civilians surrendered to Gabaldon, who turned them over to the U.S. military authorities. For his exploits, according to Gabaldon, he became known asThe Pied Piper of Saipan
http://en.m.wikipedia.org/wiki/Guy_Gabaldon