"Look at me in fancy dress- I'm a Ninja turtle!"
In the UK, 'ninja' just means that a character may have
certain martial art skills
(like the Ninja turtles) - and perhaps wears some Eastern type clothing.
"Look at me in fancy dress-I'm a Ninja turtle!" （オシャレな衣装姿の私を見て！私は忍者だ！）
英国では、"ninja"は武術を知っているキャラクターのイメージがあります（映画Ninja Turtleのように）。東洋系の服を着ているイメージもあります。
Ninja's are synonymous with Japanese culture. When someone mentions the word 'ninja' people often think of Japanese history or more recently Japanese movies.
The term ninja doesn't change between languages. It's the name of a type of fighter in Japanese culture and usually names remain the same across languages. Just like the word samurai.
In the case of "ninja" there is no word in English to describe a person who studies/trains to be a ninja.
We use the word "ninja" when describing a ninja.
English has borrowed words from many languages and the word "Ninja" is no exception. The word Ninja is even the same in Semitic languages like Arabic!
Both children and adults readily understand the meaning of the term Ninja. It is commonly affiliated with an internationally known cartoon show entitled Teenage Mutant Ninja Turtles.
English speakers use Ninja as well. We use it when speaking about Japanese culture. We also use "ninja" to describe someone who is very agile, or someone who excels at some particular thing especially fighting arts. It is also used in reference to "Teenage Mutant Ninja Turtles", a popular cartoon with ninja-fighting turtles.
映画やアニメのおかげで忍者がそのまま英語に入りました。他の言い方はmartial arts masterですが、それがあまり使われていません。海外の文化では忍者と一番近い人はspyという００７みたいな人だといわれるかもしれません。
例：I went to Koka City to be a ninja for a day. 忍者を体験するために甲賀市に行った。
ご参考にしていただければ幸いです。
A, "Ninja," is word that we use in English to describe someone who has high martial arts skills. Typically when English speakers think of Ninjas, they come from Japanese culture and they typically wear all black clothing, are very agile and quick.
アメリカ合衆国 
イギリス 
南アフリカ 
