The group is preparing a mysterious '2017 Seventeen Project', and Chapter 1 revolves around the theme 'Alone'. In his trailer video, Joshua is contemplating in deep thought at a sink. You see the words "An everlasting being whichever way it goes" and the same "Even though you are being alone, remember we are on your side and don't be afraid of all the fears you have."

'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. Joshua's prime number is 131.

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

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