The group is preparing a mysterious '2017 Seventeen Project', and Chapter 1 revolves around the theme 'Alone'. 'Prime Number' is also an ongoing motif in Seventeen's teaser series as fans have to enter the prime number seen in each member's trailers on the group's official website in order to be able to access their teaser images. His number is '103'.

SEE ALSO: Seventeen brings out the new highlight medley for their upcoming best album '17 IS RIGHT HERE'

Check out the teasers and stay tuned for more trailers from Seventeen!