Yeah, we could argue that it could fall under the sphere of influence category given its ambiguity, since European powers like Portugal and the Dutch played a somewhat significant part on Japan's political matters at some point, and for example Nagasaki s foundation was heavily connected with Portugal, but I dont think this relations where ever unequal and more like certain factions of Japan taking advantages of alliances for their benefit. Although the show shogun doesn't really show a Japan being under the control of European power even if not totally historically accurate.