Germany vs Japan: which is bigger?
Japan is bigger: 377,974 km² against 357,588 km², about 1.06 times the size of Germany.
Drop Germany onto Japan →Side by side at true size
Both drawn at the same scale on an equal-area projection.
And on the usual world map
On the usual world map it's the other way round: Germany looks 1.5 times bigger than Japan, because the map inflates Germany about 2.5 times and Japan only 1.6 times.
In numbers
Areas: official totals including inland water (UN Statistics Division via Wikidata). Outlines: Natural Earth. How Globegami works