As seen in the video below, the event adds Adol, Dana, Sahad, Laxia, Hummel, and Ricotta as playable characters to the game. Additionally, a variety of Ys VIII skins have also been added to the game as well.
Crusaders Quest is made by Korean developer NHN Entertainment, and a part of the Hangame gaming portal. This is available for both iOS and Google Play. According to details on Google Play, this collaboration has been included in the game’s most recent update, as well.
Below is the tweet with their glorious maintenance image, as well as additional information on the game’s additions with this particular update. I have found the >Korean patch notes here and have read that English ones should be out soon.
Maintenance period: 12/13 14:30 – 19:00 (PST)
– CQ x Ys VIII Collaboration BEGINS
– 6 Brand New Ys VIII Heroes ADDED
– 12 New Ys VIII Hero Skins ADDED
– Many Bugs around Schula’s Smithy SQUASHED pic.twitter.com/e6AYI968Rr
— Crusaders Quest (@CrusadersQuest) December 13, 2017