JIS Roman-letter symbols
The number row differs from US English: Shift+2 gives double quote, @ has a dedicated position and ¥ occupies an extra key near Backspace. The extra key beside right Shift adds another symbol position.
Japanese character input
The keys around the spacebar select conversion and input modes. Kana or kanji entry depends on the selected Japanese input method and its current mode. Use the Roman-symbol diagram for physical reference, then select the intended input mode in the operating system.