In the past, in Ikaho-onsen hot springs which has been called the birthplace of Onsen-manju, the water of the spring's source and the mineral deposits of the hot springs (resembling flowers) were used for adding the unique color which reminded of spring's source to the manju.
発祥の地ともいわれる伊香保温泉では源泉をイメージする色を与えるために、源泉や湯の花を配合したこともあった。