conjunction
Used at the beginning of a clause to express contrast or unexpected result, similar to 'and yet' or 'but'. Often follows a statement of fact or situation.
彼は一生懸命勉強した。なのに、試験に落ちた。
He studied very hard. And yet, he failed the exam.
天気予報は晴れだった。なのに、雨が降ってきた。
The weather forecast said it would be sunny. But it started raining.