[Torplexed]

Originally Posted by GerritJ9

To be quite honest, I don't know whether the IJN even used any of them operationally. Given the IJN's state at that time (May 1945), I doubt it. First of all, they would have to compile crews for them. And then, they would have to work up before departing on ops- and by the time they might have been ready, the Emperor had signed on the dotted line.
As a footnote to history, I wonder what happened to the German crews after Germany's surrender- were they interned by the Japanese, repatriated through neutrals..........?????????

The combined fleet site gives this summary of U-181 /I-501 final weeks. I imagine the other interned German crews pretty much went through the same routine.

6 May 1945: The Surrender of Germany:

Vice Admiral Fukudome Shigeru (former CO of NAGATO), Commander, 13th Area Fleet, three other admirals and staff officers arrive by automobile alongside Freiwald's U-181 and KK Heinrich Timm's U-862. Fukudome informs Freiwald, Dommes and Timm they are being interned since Germany capitulated. The German officers are invited to a festive dinner, "in European style", where Fukudome thanks them for their war effort.

At about 1600, trucks arrive and disembark armed Japanese troops alongside the U-boats. The DKM's swastika ensigns are lowered from the U-Boats and replaced by the IJN's battle flags. During four patrols, the U-181 sank 27 ships for a total of 138,779-tons. Later, she is overhauled by the No. 101 Navy Repair Unit at Seletar.

June 1945:
The U-boats' crews and base personnel are trucked to an ex-British rubber plantation at Batu Pahat in southern Malaya for internment.

15 July 1945:
Seletar. The U-181 is commissioned in the IJN as the I-501 and assigned to Fukudome's 13th Area Fleet. I-501 is operationally capable of conducting war patrols. The submarine's former German crew is divided into two 30-man strong parties tasked with teaching handling of the U-boat to the Japanese.

The Japanese plan to use the I-501 for training in late August, then for a transportation run to the Andaman Islands and later send her to Japan to have her torpedo tubes remodeled to accommodate IJN torpedoes. The Japanese crew of the I-501 starts a working-up course under German supervision.

16 August 1945: The Surrender of Japan:
Seletar. The Japanese surrender to the Royal Navy. The I-501 and the I-502 are moored next to the damaged cruiser MYOKO in the Johore Strait.

30 November 1945:
Removed from the Navy List. Under British supervision, her former German crew strips the I-501 of all her valuable parts.

http://www.combinedfleet.com/I-501.htm