ホワイトデー

Etymology
. There are for the origin of the custom. The most widely discussed is that it was coined by 全国飴菓子工業協同組合 (Zenkoku ame kashi kōgyō kyōdō kumiai “National Candy and Confectioners Union”) in 1978 to increase sales. Prior to coinage of the name, similar occasions for giving gifts in return of Valentine’s Day gifts were variously known as ポピーデー (Poppy Day), フラワーデー (Flower Day), クッキーデー (Cookie Day), and マシュマロデー (Marshmallow Day).

Proper noun

 * 1) White Day