Oume Goketsuji is the final boss of the first Power Instinct and serves as the series' mascot. In Groove On Fight, she appears as a playable duo fighting alongside her younger twin sister, Otane. Oume is superhuman and is very frightening. She confined herself to the mountains to train and master her mysterious special attacks and fighting style. Oume has an eerie and unearthly presence about her. It's rumored she can turn her enemies to stone just by looking at them. She has always hated her sister, Otane, since they were young.

Ever since she Oume a child, she was combative and competitive. She began training at a very early age which gave her incredible ability and strength later on. When she was 10 years old, she was already able to defeat expert martial artists one after another. Oume despised any sign of weaknesses, so when her mother (Oshima) set her up with an arranged marriage to Kanji Kokuin, she realized Kanji's strength was inferior to her own and constantly treated him poorly and humiliated him. After a while, Kanji could not stand the abuse any further and divorced Oume just two weeks after their wedding.

At the age of 18, Oume participates for first time in the Goketsuji Tournament, defeating her mother in the finals, and became the head of the Goketsuji clan, being undefeated for many years.