Honestly man learning Japanese for your career seems like a waste of time. It's a very hard language, it's expensive and if you ever have to do business with Japanese people you will be better off hiring an interpreter. Japanese companies will always prefer hiring a Japanese national over a foreigner even if he speaks perfect Japanese too. Career-wise I think that the only situation where learning Japanese makes sense is if your boss told you you must relocate to Japan.
I think however that learning it as a hobby is very respectable and may even be useful someday, but to boost my career I would rather choose German (most European industry is located there therefore a big labor market) or French (easy to learn for a Spanish speaker, useful, etc.).