The designers at the time created both Mature and Vice with the image of a "ruthless woman" and a "cruel woman" respectively. Their origin story was mostly based on the notion of Rugal employing secretaries prior to The King of Fighters ' Both women were unavailable during location testing and were likely finished near the end of the game's production schedule. One of the Hakkesshu , Mature joins forces with Vice to serve her master, Orochi.
The two took orders from one of the Four Heavenly Kings of Orochi, Goenitz , even though they didn't like him. She and Vice were ordered by Goenitz to keep an eye on Rugal , who was attempting to use Orochi's power, so they posed as his secretaries. When Rugal was killed, Goenitz ordered Vice and Mature to follow Iori Yagami , due to his Yagami heritage of the Orochi power, and bring him to the tournament. Goenitz was defeated by Kyo Kusanagi and Iori at the end of the tournament, but Vice and Mature betrayed him, deciding Iori was a better ally to help them awaken Orochi.
Mature was developed as a "ruthless woman" by the chief game planner of The King of Fighters ' Things became hectic when the concept began being developed as a character, until a staff member suggested that Rugal's secretary from The King of Fighters '94 be used as base. Many of Mature special moves are music references. Also, Metal Massacre is not only a very early song by Metallica, but it is also the name used for various compilation albums dating back to the early 80's.
Mature is one of the major antagonists from The King of Fighters video game series, originally appearing in The King of Fighters ' However, after Goenitz was defeated by Kyo Kusanagi and Iori at the end of the tournament, but their plan backfired however, as the two can take the form of solid shadows in the living realm. She and Vice state they will meet him again in his dreams. Like in the previous tournament, Mature looks forward to seeing Iori fight with his flames. After the climax of the game, Mature and Vice will not stop Iori who will seal Orochi.