German, Italian, and Japanese submarines in the Indian Ocean

Did German and Japanese naval forces operate in the same theatre?

Their submarines did in the Indian Ocean, where Italian submarines also operated.

German, Italian, and Japanese submarines all operated in the Indian Ocean, so British convoy operations there faced a genuine undersea threat. Their cooperation also created an identification problem for Japan because several different friendly submarine types shared the theater. That uncertainty could hinder anti-submarine warfare by delaying the decision about whether a detected contact was hostile. British submarines could exploit the resulting hesitation over identifying a contact.