What it means
ことに has two main uses. After an emotionally evaluative plain form, it highlights the speaker’s reaction to a fact, often meaning “to my surprise,” “fortunately,” or “regrettably.” It can follow a past-form verb, an i-adjective, or a na-adjective with な. In the adverbial pattern ことに + noun phrase, it means “particularly” or “especially,” and commonly introduces a topic such as a season, place, or situation.
Usage note
Do not confuse the adverbial pattern ことに + noun phrase with the emotional pattern [plain form] + ことに. The adverbial use normally comes before a noun phrase, as in ことに冬は, rather than directly before a plain-form clause.
How to use it
ことに冬は、海辺でも風が強いです。
Particularly in winter, the wind is strong even by the seaside.
意外なことに、彼はその難しい試験に合格しました。
To my surprise, he passed that difficult exam.
悲しいことに、長年の計画が中止になりました。
Sadly, the long-standing plan was canceled.
驚いたことに、予定より早く電車が到着しました。
To my surprise, the train arrived earlier than scheduled.
ことに冬は、海辺でも風が強い。
Particularly in winter, the wind is strong even by the seaside.
意外なことに、彼はその難しい試験に合格した。
To my surprise, he passed that difficult exam.
悲しいことに、長年の計画が中止になった。
Sadly, the long-standing plan was canceled.
驚いたことに、予定より早く電車が到着した。
To my surprise, the train arrived earlier than scheduled.
Example sentences
驚いたことに、閉館後の図書館にまだ明かりがついていた。
To my surprise, the library still had its lights on after closing.
ありがたいことに、駅員が落とし物を見つけてくれた。
Fortunately, a station employee found my lost item for me.
残念なことに、予約した講座は定員に達していた。
Regrettably, the course I had registered for had reached its capacity.