I paid around 4000 Yen for a 3gb data sim at the airport when I got into Japan. Finding another one when that ran out cost me around another 3500 for 3gb, and I had to go all the way to a big electronics shop to find it. This one costs less, provides more than 3x the data, and saves you having to waste more money and time to get over to an electronics shop. Absolutely 0 problems. Just popped it into my iPhone, and I was on my way. Awesome product.