Mai Valentine is a video game depiction of Mai Valentine, a character from the Yu-Gi-Oh! anime. She is available as 2 different Super Partners, with a default of 5 Rental Points (as opposed to a Legend Partner, like most partners based on characters from the anime). Her normal partner version has a partner ID of P114, while her Orichalcos version has a partner ID of P124.
She also appeared as an opponent under Duel Monsters Arena mode, using her normal avatar image.
As a partner, Mai was only obtainable through 2 special events, lasting from:
July 16, 2014, 10:35 (UTC) through August 26, 2014, 23:59 (UTC) (her normal version)
October 8, 2014, 10:00 (UTC) through October 29, 2014, 23:59 (UTC) (her Orichalcos version)
Players who spent Miniclip Credits in-game, before the maintenance period of a Wednesday during the first time period, were qualified to receive her in their Gift Boxes (which they did after the maintenance period of that applicable Wednesday). For the second time period, players who spent Miniclip Credits in-game during that time period were qualified to receive her in their Gift Boxes after maintenance on November 5, 2014.
Once players received the normal version as a partner, they could increase her Rental Point maximum by 1 (and simultaneously fully refresh them) by qualifying to receive her again during that first time period, up to a maximum of 8 Rental Points.
"Sky Scout" is most likely included in this character's Deck (post-October 21, 2014 maintenance) as a reference to how it was incorrectly named "Harpie's Brother" before, as it is not actually a "Harpie" monster.