なぜか

Adverb (usually used in formal writing and formal speech) (Advanced 370)

An adverb indicating that the speaker/writer doesn’t know the cause of/reason for something

Equivalent: I don’t know why; without knowing why; for an unknown reason

このところなぜか体の調子が悪い。
I don't know why, but I haven't felt well lately.
ヨーロッパやアジアには受け入れられなかったSFが、なぜか日本には根づいた。
Science fiction, which did not catch on in Europe and Asia, took root in Japan for some unknown reason.
なぜか僕は日本語の難しさにはまってしまった。
For some reason, I got hooked by the difficulty of Japanese language.
最近私が住んでいる町ではなぜか古本屋が増えている。
I don't know why, but lately the number of used bookstores (in the town) where I live has grown.
ログインの手順を教えて下さい。なぜかできなくなってしまったんです。
Please teach me how to log in. I don't know why, but I can't do it anymore.
自分の文化のリズムには、なぜか体が自然と反応し、踊りたくなる。
For some unknown reason, our bodies respond spontaneously to our own cultural rhythms, and we feel like dancing!

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