I'm extremely leery of these kinds of contests claiming that they can help make your career.
Art contests tend to be exploitive by their very nature. If you create art for someone, you should be paid for it. You shouldn't have to battle with other people for the PRIVILEGE of being paid for your art. I can see some exceptions when a contest is clearly just for fun, but if it's for an actual business or job or career opportunity, it should be treated like a job.
Also, the legalese for this contest says that once you submit a comic for their contest, you grant them the right to publish your work without compensation:
Regardless of whether you are awarded a prize, by submitting your manga, you grant the SILENT MANGA AUDITION Committee, without compensation, the non-exclusive right to publish, use, adapt, edit and modify your manga, including by displaying your manga on the internet, and to use your name, age, country and other information you provide in connection with your work or the SILENT MANGA AUDITION®. The submission will be considered as published in Japan first, and will therefore be subject to the copyright law of Japan.
I'm not gonna tell you what you should and shouldn't get involved in, but I want to make sure you realise that this isn't normal or reasonable expectations for the comics industry. I've been involved in a couple of comics anthologies and both of them worked out payment BEFORE the art was created -- generally, you submit your portfolio and your pitch, and then if they accept you for the anthology then you sign a contract working out what you promise to create and what they promise to pay, and THEN you create the actual finished art for them. Anyone who asks you to create something in full before they judge whether they'll pay you for it or not is already taking advantage of you -- imagine if someone wanted to commission you and then said "I'll only pay you if I like it, though." You wouldn't want to work with that person! And them getting rights to use your work whether they pay you or not seems even worse to me.
I can't say for sure that nothing good could come out of it -- I've not heard of this particular contest before, myself. If you just wanna make 16 pages for the challenge and throw them at the contest because you don't super care what happens to them or who ends up with rights to them, then that's cool, that's totally your prerogative! But I'd be wary of it, personally; I don't really like to support this kind of thing.
