It has been suggested that this article be renamed to Risa Kageyama. (discuss) The reason given was: Risa is the only notable/credited character out of the three. The other two sisters can be linked back to this page.
The Kageyama sisters are three witches who want to have the three Hecate witch cards. Risa Kageyama (影山 リサ, Kageyama Risa) wants to take Yugi'sViolet Hecate (バイオレット ヘカテー, Vioretto Hekatē) card. After pretending to be Yugi's friend, Risa reveals herself to be one of the sisters. Yugi, with the Millennium Puzzle taken away from him, is forced into a Duel Monsters game with the Kageyama sisters. Yugi is about to lose when Kaiba appears and takes over. Kaiba defeats the Kageyama sisters in Duel Monsters, explaining that he should be the one to defeat Yugi.
When it comes to regular life Risa and and her sisters are beautiful girls with sweet kind, and helpful personalities, but when Duel Monsters is brought into into the mix, their obsession with the game drives them to do cruel things that they would not normally do, so they can get the cards that they desire.
The Kageyama sisters collectively play a Hecate deck focused on slowly summoning their "Gorgon" card. Their deck employs little strategy, and uses the (relatively) high ATK of each "Hecate" to ward off the opponent until their ace can be summoned.