Japanese people have a rather contemporary outlook
It depends really exactly what you mean to say. If you are talking in terms of fashion or music, perhaps, then the first example sentence may be appropriate. More generally, the second sentence may fit. However, if we say, '..take action..' it usually means make a decisive move, and often, as a response to something someone else has done. You do NOT 'take action' for example if you see a new style of dress and then go out and buy something similar. That is following fashion, or a new trend in clothing, not, 'taking action'.
これは、本当に何を言いたいかによると思います。
もし、ファッションや音楽について話したければ、最初の例文が適しています。もっと一般的に言いたければ、二番目の例文が良いでしょう。
しかし、「take action」を使うときは通常、断固とした行動に出るという意味です。また、他の誰かがしたことへの対応として頻繁に使われます。
例えば、新しいスタイルのドレスを見て似たような物を買いに行くのに、「take action」とは使いません。これは、「following fashion」、または「following a new trend in clothing」と言い、「take action」とは言いません。
People in Japan will do whatever everyone else is doing if its trendy.
People in Japan love following the latest trends.
You can say 'people in Japan' or 'Japanese people' when talking about whom. When people do something that everyone else is doing we call this a 'trend', 'craze', or 'fad'. This just means everyone is doing.
「主語」には「people in Japan (日本の人たち)」や「Japanese people (日本人)」が使えます。
「trend」や「craze」、「fad」は「みんながしていること」を表します。
Normally Japanese people will do something if others are doing it.
When we talk about the people of Japan, it is important to add the word people to Japanese because it can refer to any part of Japanese culture. We use "normally" to talk about typical activities. I hope that this helps. :)
When you do something because alot of other people are doing it then you are said to 'follow the trend' meaning something is popular to do (trendy)
'follow the crowd' is a common pfrase used to describe follow what other people are doing
何かを「他の多くの人がやっているからやる」なら、これは 'follow the trend' と言えます。'trend' は「流行」の意味です。
'follow the crowd' は「他の人たちに従う」の意味の一般的なフレーズです。
"Japanese people will take action if they hear that everyone else is doing it"
"Japanese people will follow the actions of others if it is a popular decison within their community"
If you wanted to explain that Japanese people will take action if they hear that everyone is doing it, you could say either of the following: "Japanese people will take action if they hear that everyone else is doing it" or "Japanese people will follow the actions of others if it is a popular decison within their community". Both these sentences adequately explain what you are trying to convey.
日本人はみんながやっていると聞けば行動すると伝えたいときは、以下のように言うことができます。
"Japanese people will take action if they hear that everyone else is doing it"
（日本人はみんながやっていると聞けば行動する。）
"Japanese people will follow the actions of others if it is a popular decison within their community"
（日本人は他の人が決めたことが評判がいい知れば、その行動に従う。）
これらはどちらも、ぴったりのフレーズです。
Japanese people are quick to jump on the bandwagon
"Japanese people like to follow the crowd"
"To follow the crowd" is an idiomatic expression that means that someone is happy to or has a tendency to do something that a lot of others are already doing. "Crowd" means a big group of people gathered together in the same place.
"Japanese people are quick to jump on the bandwagon"
"Jump on the bandwagon" is a commonly used idiomatic expression that means that someone quickly or easily joins in with what others are doing or saying. It is slightly pejorative because it infers that someone is joining in with something because it is popular or successful, rather than thinking for themselves.
"Japanese people like to follow the crowd"
（日本人は大勢の人に従うのを好む。）
"To follow the crowd" とは、他のたくさんの人がやっていることをしたがるという意味のイディオムです。"Crowd" とは、同じ場所に集まっているたくさんの人の集団のことを意味します。
"Japanese people are quick to jump on the bandwagon"
（日本人は、周囲の人がやっていることと同じことをする。）
"Jump on the bandwagon"は、みんながやっていることとすぐ同じことをすることを意味します。考えずに、みんながやっているからとか、うまくいくからなどの理由で何かをすることを表すので、やや軽蔑的な表現です。
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