Drill straight through the center of the Earth from Tokyo, Japan and you'd surface on the exact opposite side of the planet — its antipode.
Tokyo's antipode sits at 35.68°S, 40.35°W, in the southern hemisphere, west of Greenwich. That places it in or near the Atlantic Ocean.
It lies roughly 20,015 km from Tokyo — about as far apart as two points on Earth can possibly be. And the relationship is symmetric: the antipode of that spot is, of course, right back here in Tokyo.
Tokyo's antipode falls over open water, in or near the Atlantic Ocean — water covers about 71% of the globe, so antipodal land pairs are rare. The nearest named place is Praia Pai João, a beach in Brazil, roughly 1,091 km away.
Antigea's live map shows the satellite view, the closest Street View, and the local time on the other side of the world.