害 is one of the most commonly used Japanese kanji, and it also has a lot of special readings in addition to the standard onyomi and kunyomi readings.
ONYOMI 音読み
KUNYOMI 訓読み
ガイ gai
Examples
ワインは本来害にならない。Wine is not harmful in itself.害になる薬もある。Some medicine does us harm.コーヒーは胃に害を与える。Coffee does harm to your stomach.喫煙は健康に害がある。Smoking is harmful to health.喫煙は君に大いに害になる。Smoking will do you a lot of harm.たばこは健康に害がある。Smoking is dangerous to health.長雨は植物に害をおよぼす。A long spell of rainy weather is harmful to plants.悪い本は害を与える。Bad books will do you harm.彼は害になるほど酒に溺れた。He had taken to drinking more than was good for him.たばこを吸うことは害を与える。Smoking does you harm.