Full Moon

Mystery Codes
The teasers have a specific chapter opened in the book for each day. The numbers correspond to a letter in the reversed alphabet. 21-6-15-15-14-12-12-13 = F-U-L-L-M-O-O-N. Coincidentally, they fit perfectly into the reversed alphabet too and form an anagram for the title U-F-O-O-N-L-L-M.

Every day, the number of crystal balls on the table increases.

The members were also writing words on the same notebook. The final message reads "시간", "달빛", "비밀", "꿈", "약속", "따스함", and "우주". They translate to "time", "moon", "secret", "dream", "promise", "warmth", and "universe".

The books on in the background are slowly revealed by each member every day, and the words on the titles of the books have the initials to form the title of the song.
 * The Final Hour
 * Soil Mechanics for Unsaturated Soils
 * Little House on the Prairie
 * Lady in Blue
 * MAGIC
 * The Odds Against Me
 * The Oxford Book of American Light Verse
 * Net Ready