The primary risks relevant to making derivative transactions are market, counterparty and liquidity risks. We should consider these three uncertainties when dealing with derivative transactions.
Market risk is the possibility for an investor to experience price fluctuations derived from financial markets.
Counterparty risk is a probability for each party of derivative transactions that the counterparty cannot continue its contractual obligations until the end of transactions due to its bankruptcy.
Liquidity risk is the risk derived from the lack of derivative transaction volume that cannot be bought or sold quickly enough to prevent or minimize a loss.

There are a lot of factors which move financial markets. For instance, market participants were paying attention to political events such as UK referendum, U.S. presidential election, and French presidential election over the last year. In order to prepare for unexpected results, market participants such as pension funds, insurance company or global companies were utilizing the derivative transactions like "Put option" before the events.

America does definitely. American financial market is by far the biggest in the world and every market participant is paying attention to the political events of America. As you may remember, global equity market clashed immediately after announcing the unexpected results of U.S. presidential election last year.

I know where you are coming from, but America actually has great influence on today's financial market, so we cannot pay attention to the country whether we like it or not.

(I'd like to amend following the last message from "we cannot pay attention to" to "we cannot help but pay attention to".)

Japan still has the certain level of influence on global economy as you mentioned, but it is getting smaller gradually year after year.
As for the contribution in technology industry, new competitors like Taiwan or South Korea are standing out as a market leader in recent years.