Confident Rider
The Confident Rider status must be obtained before the unicorn horn can be unlocked. The most efficient way to obtain this rink is to compete in all of the "Free Ride" competitions. Complete the challenges, beat time limits, and achieve high scores to gradually increase your skill level. If you have completed the "Free Ride" competitions and have not yet obtained a Confident Rider rank, you can repeat previously completed stages to gain extra experience.
The Quadrangle
The Quadrangle event is a special stage in which the player races against the clock to compete an obstacle course. While this stage is also used to gain points and experience, it is the secret means by which players can unlock the unicorn horn. To unlock the unicorn horn, you must have the fastest time in the quadrangle event. Because the current first place time is 24.10, you must achieve a time of 24.09 or better.
Equipping the Unicorn Horn
The unicorn is not an entire horse; rather, the unicorn horn is an accessory that can be added to any existing horse to change it into a unicorn. Visit the stables and select the "Costume Horse" option. In this menu, you can add decorations to the horse. Select the unicorn horn and equip to a horse to transform it into a unicorn. While the unicorn horn does not have any significant statistic bonuses, it does drastically change the appearance of the horse.
Unicorn Horn Delay
"Silver Buckle Stables" can occasionally experience a delay between events wherein the game records a change in variables, but the effect of those changed variables don't register. As a result, the unicorn horn might not be immediately available upon beating the quadrangle. If the unicorn horn is not available in the "Costume Horse" section, exit and reenter the stables until the option appears. Once it has appeared, you can equip it to any of the horses you own.