It's idle to think you can change the world by yourself.
自分１人の力で世界を変えようと思ってもむなしいことだ
It's just 3 o'clock.
３時きっかり
It's just a friendship thing.
（男女が恋愛関係ではなく）単なる友人（関係）だ
It's just a joke.
ほんの冗談だよ
It's just a phase he's going through.
((略式))そういう年ごろなんだ
It's just a thought.
((略式))１つの考えとして言ってみただけだけど
It's just like him to do something like this.
こんなことするとはいかにもあいつらしい
It's just what I wanted.
ちょうどこれが欲しかった
It's kind of you to invite us.
お招きありがとうございます
It's late and I must fly.
((略式))遅いから急いで帰らなくちゃ
