Katsuragi Calypso

Katsuragi Calypso, commonly referred to as Calypso, was the main antagonist of the Shadow RPG arc in Dark Game!, and a major supporting character in the anime, Spirit Chi Warriors!. Initially a villain, Calypso's goal was to murder Yugi Typhoon and his friends at all costs. However, after her defeat, she reveals to Yugi at the beginning of the second series, that it was simply a test for Yugi. She is an old oracle who knows of every single event that ever takes place. She usually supports the heroes by giving them info of upcoming dangers and how they should take about in stopping them, usually ending up being right. She has stated that her favorite/greatest comrade was Yugi Typhoon. She is one of the many mentors of Yugi throughout the series, always keeping an eye on his progression as a martial artist, admiring his determination and goal to balance out peace and justice throughout the world.

Masu
Masu (サクラマス) is a disguised form of Calypso. She does this by infusing her body and soul within the vessel of a young female. She has also wrapped herself with bandages from head to toe, in an attempt to mask her own power, as well as conceal her identity. Calypso first introduces this form prior to the Second Phase of the Battle Testimony tournament.