YOU SAID:

Sorry for our careless mistake but we were looking for the unreserved seats

INTO JAPANESE

不注意なミスで申し訳ありませんが、予約されていない席を探していました

BACK INTO ENGLISH

Sorry for the careless mistake, but I was looking for an unreserved seat

INTO JAPANESE

不注意なミスで申し訳ありませんが、私は自由席を探していました

BACK INTO ENGLISH

Sorry for the careless mistake, but I was looking for a free seat

INTO JAPANESE

不注意なミスで申し訳ありませんが、無料の座席を探していました

BACK INTO ENGLISH

Sorry for the careless mistake, but I was looking for a free seat