Hideo Kojima posted photos on his Twitter of the special 25th Anniversary Metal Gear t-shirts, which will be available at UNIQLO Japan starting today. The shirts will be available in limited quantities. They will also be for sale at UNIQLO stores worldwide (in response to questions on Twitter Kojima confirmed that UNIQLO US, UK, France, Singapore, China and Malaysia will have them), but three limited edition prints are only for sale at UNIQLO Ginza, in Tokyo, one of them being Metal Gear Rising Revengeance themed.
This shirt is exclusively available at UNIQLO Ginza, Japan, starting April 28th.
Kojima visited the store in Tokyo and took photos of the opening. It seems like people where lined up outside.
You can see all the different t-shirts on this page. Here is the Japanese UNIQLO page where the shirts can be bought for ￥1,500. They will be available this May at UNIQLO UK, for £14,90. As stated, they will also become available at other UNIQLO stores worldwide.