どういうわけか

expression

somehow; for some reason

Expresses that something happens or is the case without a clear reason; often used when the speaker finds the situation puzzling or unexpected.

• どういうわけか、今日きょうは電でん車しゃが空すいている。

  For some reason, the train is empty today.

• どういうわけか、彼かれは急きゅうに怒おこり出だした。

  Somehow, he suddenly got angry.