Scenario Mode is only available in the Global (US) version of Kartrider. It gives you missions to do, with you as Dao. As of yet, there is only one chapter: A New Rider.
Chapter 1: A New Rider
Just race through Arc Enemies for 50 Lucci.
Prove your worth to Diz!
Again, race through Arc Enemies. This time, though, you have a time limit, and the reward is 500 Lucci. Don't drift, just drive. You should finish in time easily.
A Duel Against Diz
Outrace Diz in Woodland for 200 Lucci. Again, you can easily finish this without drifting.
Complete the track (Penguin Cave) in 2:09. Your reward is an Arctic Rim License Plate for seven days.
Kart Outlaw Chunk!
Beat Chunk in Oasis for 1000 Lucci. It's easiest (though boring) if you don't drift.
Race through Woodland in 2:12 and you'll get 200 Lucci.
Delivering the Kart to the Bizarre Bazaar!
The second of Mos's tasks is to deliver a kart to Maridia within 31 seconds for 500 Lucci. You'll have to maneuver around the obstacles - she won't want a beat up kart. You're allowed one collision - on the second, you have to try again. Don't rush, you'll hit everything, but don't go too slow, either, or time will run out.
Prove That You're Worthy!!!
This is the first scenario level that doesn't involve racing against time or a computer. For this one, you'll have to race ten times in multiplayer. Your reward? A three-day corndog baton.
Mos's Hidden Talent!
After finishing the three tasks, you must defeat Mos in a race. Just race through Penguin Town and get to the finish before him for 1000 Lucci.