The basic idea is a decent one, an octopus-themed deck with a Japanese style. But this is the kind of deck that would have done great maybe five years ago - today, this alone won't be enough, I don't think, to make a dent in the Kickstarter crowd. It might be appealing to magicians, but there's not enough magicians out there that would be interested to make this successful unless you manufactured it dirt-cheap, in which case the quality would drive people away. The faces are quite literally generic, aside from your octopi - not enough.
All-black decks are starting to make a comeback, but it's a tricky proposition - they look lovely out of the box, but eventually even the best-made black decks will start to chip at the edges with repeated handling and shuffling. With a white deck, chips are no big deal because the paper underneath is white - but a white chip on the edge of a black card stands out like a sore, blood-dripping thumb wrapped in six feet of gauze.
It is indeed possible to make a card back with so much solid area on it. But I know that USPC tends to advise against this - a single air bubble of ink on a card back will ruin it because there's so little by way of a design to conceal it. Should you have decks ruined by air bubbles with this much solid color on the back, USPC won't take them back as defective, considering it a design flaw that's the designer's responsibility, not the manufacturer's.
And I haven't even begun to touch on the subject of a popular form of media in Japan: tentacle porn... That's a minefield best left undisturbed - or perhaps exploited, if you want to go that route!
These days, the tuck box is almost as important as the deck itself. I know of collectors that will buy a deck based more on the packaging than on what's inside - collecting the cards is something of a fetish for them, but if it makes them happy, more power to them. What do you have on tap for that?
Consider something that will jazz up the design overall. Custom pips, even if they're basically the same shapes as traditional, can help. Unique index fonts are another way to go. Basically, you need to make this a little bit more custom than what you have if you want to get any real market penetration - you're up against a lot of competition these days. With what you have now, it's roughly equivalent to going up against a major ice cream chain store by offering a slightly different flavor of vanilla and nothing else. (Octopus-vanilla?) Kidding aside, you want a little more oomph in this design if you want people to pay it attention.
Here's a simple idea, off the top of my head - it's an octopus deck, so why not have them in their natural habitat? Make the deck background a deep ocean blue, perhaps with a fade-to-white border or borderless. Borderless, despite its drawbacks, is popular with collectors and makes for gorgeous art decks.
Another idea - it's an octopus deck, you have a lovely little octopus there. Why just four? Do MORE with the theme - octopi for court cards, perhaps? Make the pips in their standard shapes, but as fish? Throw more IMAGINATION into your theme.