What is this blue badge that Prime Minister Shinzo Abe likes to wear?

After seeing a picture on Donald Trump's Twitter featuring Shinzo Abe and then visiting the Wikipedia page about Shinzo Abe, I noticed in the two pictures he's wearing the same two badges on his suit jacket.

I can see that the golden/yellow badge is clearly a chrysanthemum, one of Japan's national symbols, but I do not know the significance of the blue badge. What is this symbol and what is its significance?