After first seeing that unusual tanker class in AOD, I have finally found out what it is. In case anyone does not know what I am talking about, it is the Coastal Tanker (NCOT) that I kitbashed from the Tugboat and which was also in AOD, CAOD, SH1, and Danger from the Deep.
It was a Japanese design, as I have suspected, and there were two (as there were in AOD:hmm

. The larger class was known as the Juyusen class, and were 906 GRT (the exact tonnage they had in SH1

). The smaller class was the Suisen class, and were about 150-233 GRT (very small ships). The Juyusens were used to transport fuel between shipyards and bases through coastal waters, and the Suisens were used as water transports. A few of both classes survived the war to remain in merchantile service. I imagine that other nations would have had similar tankers, but I am not sure.