なぜWhy

なぜ is the formal way to ask 'why' in Japanese. It is often seen in writing, formal speeches, or in serious situations when asking for a logical reason or cause for something. As it is direct and formal, it can sound slightly stiff in everyday casual conversation.

Of the three common ways to say 'why' in Japanese, なぜ is the most formal, followed by どうして, with なんで being the most casual.

Fun Fact

Although slightly rarer, なぜ may also be seen in its kanji form 何故(なぜ), literally meaning 'what cause'. As with a lot of words which are normally written in kana but may sometimes be written in kanji, 何故(なぜ) will more typically be seen in more formal or literary writing.