From Nesis, it sounds like
S. prashadi is pretty big (14cm mantle length.) It says it's got 2 "enormously large" and 2 somewhat smaller suckers on each club. Found "From the Red Sea and Gulf of Oman to Zanzibar, Madagascar, Mauritius, and Eastern India. Outer Shelf. Fairly common in the Red and Arabian Seas. Fished locally."
Also from Nesis,
S. kobiensis is described as probably a species complex, also mainly outer shelf, ML 7cm infrequently 9cm, Fished in southern Japan and China. Found from southern Hokkaido, Honshu (both coasts) and the Yellow Sea to the Philippine Islands and Gulf of Tonkin and the northern part of the Indian Ocean from the Arabian Sea and Persian Gulf to Burma.
Norman has nothing on prashadi, but describes kobiensis:
body to 7cm, dist. Japan to at least S. China Sea, abundant in shallow waters to at least 150m, recognized by iridescent red-pink markings of a v-shaped strip above each eye and stripes on the 1st to 3rd arm pairs.
Since these are both species fished for food, you can find some info on them in the FAO guide as well (which I won't bother to copy):
http://www.fao.org/docrep/009/a0150e/a0150e00.htm