It's not an easy language to master even if you lived full-time in Japan. Everything about the language is needlessly complicated. The grammar, the writing system, the social conventions that influence word choices. Anime Japanese is its own kettle of fish. Overly colloquial or stylized samurai talk - neither of which you'll get taught in most language courses.
Now, you could be a savant who picks it up in no time. More likely you'll be in it for a couple of weeks and give up - or life. It's not a bad hobby. Even beyond Duolingo you'll find plenty of resources online and lots of it free.
Consider the needlessly complicated to be applied on top of a general baseline of needlessly complicated that applies to any language.
While they don't have gendered nouns, they have something equally unnerving for the beginner learner. Their noun classes evolve mostly around the nature of shapes and sizes, which becomes an issue the moment you need to count anything. For which there are two systems, one of which stops at ten, and the other is highly irregular in its forms. And don't get me started on the calendar. English is relatively unsophisticated by comparison.