If you wanted to invest directly yourself in the Nikkei 225 you would need to buy equal amounts of each stock in the index, which would be prohibitively expensive for nearly every investor. Even though there is no direct way to invest in the Nikkei 225, but there are exchange traded funds that mimic closely the movements in the Nikkei 225. There are several ETFs that track the Nikkei 225 trade on the Tokyo Stock Exchange. They include Blackrock Japan’s iShares Nikkei 225 ETF, and Nomura Asset Management’s Nikkei 225 Exchange Traded Fund.