What is the event 'Love 100 days later'?

The event ‘Love 100 days later’, is an event hosted on an international flight departing from Incheon which you can receive your postcard in 100 days that you
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Please write down the contents and address on the postcard you receive on the plane, and it will be mailed in 100 days. However, depending on the in-flight situation, the event may not proceed.