Many Japanese people say "Kochijan" (some products in Japan have this label) but I believe that the "proper" Japanese name for this condiment is "Kochujan" (コチュジャン).

The original Korean word 고추장, might be "Kochujang" or "Gochujang" in English.

However, when I hear Koreans speaking, they seem to hit a sound that falls between "ch" and "ts" sounds. So it could easily sound like "Kotsujan" (*)

(*) Hence the question "What's 4 X 22?" that street thugs used at roadblocks to identify Koreans after the Kanto earthquake in 1923.
(Answer = "Hachiju-hachi" which gave away many Koreans whose Japanese was otherwise undistinguishable from native Japanese speakers). Perhaps they'll employ this shibboleth to sort us into the appropriate lines at NRT from November 22.