There is a special twitter campaign happening with nine winners of an "extravagant gift" but its only open to Japan residents. The prize seems to be either high quality cherries, gyutan (cow tongue), or 10,000¥ travel ticket. The campaign ends on January 7th.
To enter:
1. Follow the account @aiambesttoo
2. Go to this site
https://avex.jp/ai/aiambesttoo/?campaign and click on a gif of the track that has a memory for you
3. Post your memory in the text box and tweet it!
Winners will be contacted by direct message.
Also if you take a look at that site, you'll see the upcoming tracks of the countdown in order. That ruins the surprise!
Countdown 20 - Kumuri Uta