I'm not sure that those look like tataki nomi. Tataki nomi are large chisels for timber framing. They're not ridiculously long like some of the western socket chisels, but they are in the neighborhood of 11 inches long or a foot, and they're very heavy and not suitable for regular bench work.
The description that rutlands has there doesn't have the normal stuff in it. There are alloy steel chisels, as they call them, that are high speed steel, but they're very hard.
There are also entry level chisels that are machine laminated and made for about $15-$20 each that are 60 hardness, but they are usually carbon steel of unspecified type. The entry level chisels are still usually decent chisels, sometimes they require an extra degree or two on the bevel to prevent chipping, but they are not soft compared to western chisels.
I'd call them if I were interested in those chisels and find out how long they are. If they are closer to 8 or 9 inches long, they're oire nomi. If they are more like 11, they are tataki, and tataki are too big for general use.