@Tamerlane @alacaelum @Kaduufrrj @RealSaMu
It wouldn't be a TSA (Transportation Security Agency) agent but a CBP (Customs and Border Protection) officer inspecting international arrivals at a U.S. airport.
Visitors from Japan (and many other countries) can visit the U.S. for tourism or business for stays of 90 days or less without obtaining a visa through the Visa Waiver Program (VWP). VWP travelers are required to apply for authorization though the Electronic System for Travel Authorization (ESTA), a fully automated, electronic system for screening passengers before they begin travel to the United States under the Visa Waiver Program.
Almost all customs officials are rude to travelers. In my own experience, British, French, Japanese, and Korean customs officers were rude at best. Even upon returning to the U.S., the CBP officers were rude.