Japanese whalers in the Antarctic waters according to the Dutch magazine Marineblad dated 1939 no. 12

An item referred to the magazine Shipbuilding&Shipp. Rec. dated 26 October 1939 which reported that as a result of the war broken out in Europe Japan possessed the monopoly on whaling in the Antarctic waters. The Nippon Marine Products Company fitted out in a fast tempo the 3-19.000 ton mother ships called Tonan Maru 1,2 and 3 which would leave on 23 October Japan with 23 auxiliary vessels. Another mother ship the 17.548 ton-Kyokuyo Maru of the Kyokuyo Whaling Company with 8 auxiliary vessels and the 2-17.000 ton mother ships Nisshiu Maru No. 1and 2 fitted out by a third company with 19 auxiliary vessels would depart from Yokohama. The first mentioned company decided to transport the complete bodies back to Japan and fitted out for this purpose the 10.000 ton reefer Itsukushuma Maru while the second company fitted out the mother ships with cooling equipments with a capacity of 500 tons and chartered 2-2.000 ton lighters to transport the catches towards Japan.