(Seoul) K-Pop superstar group BTS released their memoir in South Korea on Sunday, celebrating their 10th anniversary and eagerly awaited by their fans.

“I’ve been here since 9 a.m. and finally got the book,” exclaims Aqilah, a Malaysian fan, outside Gwanghwamun’s Kyobo Bookstore, one of the biggest in Seoul.

Beyond the Story: 10-Year Record of BTS was co-written by South Korean journalist Kang Myeong-seok and members of the group, according to its American publisher Flatiron Books. It also appears in the United States where it has already risen to the top of the best sellers on Amazon thanks to pre-orders.

The memoir’s July 9 release date is a nod to an important date in the band’s history: the day their fan organization, known as ARMY, was born, there are 10 years.

BTS, which debuted on June 13, 2013, has popularized South Korean music across the globe, earning billions of dollars by building a global fan base.

A special set of stamps unveiled in May by Korea Post had been sold out, with the 120,000 sets available taking only three hours to disappear after they went on sale.

The group is currently on hiatus since two of its members are doing their mandatory military service in South Korea.