103 recent reviews on Amazon.co.jp were negative. They appear to be suspended. Data updated on .
YSIYA no longer has any products listed for sale, based on this we assume that Amazon.co.jp has taken action and very likely suspended them. Reading most up to date reviews will have more details about customer frustrations.
If you have already placed an order, but since realized that your product is likely never going to come try contacting the seller on Amazon.co.jp. If the seller is not replying, read on what to do if you were scammed.