The Japanese word for lemon is remon (English loanword) and lemon tree is remon noki.
|Remon no kawa||レモンの皮|
Interesting facts about lemons in Japan
The very first lemons in Japan came from India via China in 1818, but the citrus wasn’t grown domestically until 1898. Today, various citrus fruits, including lemons, are grown all across the country. And despite local lemon production increasing by 400% over the last 20 years, a lot of lemons consumed in Japan are still being imported.