The new 13-member boy group Seventeen revealed a picture for their fans.

"Thank you to everyone who congratulated us on her debut. It's time to shine! We'll try our best," posted Seventeen on their official Twitter account on Sunday.

In the picture, Seventeen members are making the '17' heart sign at the camera. They're also holding a blue cake made specially for them.

A short video clip was also revealed.

"We were able to successfully finish our first week of activities thanks to you. We'll always be trying our best," posted Seventeen on their Facebook.

Seventeen held their debut stages last week with their first mini album 17CARAT.