One Direction, the Irish-English band, is currently the most popular boys band in the world and has millions upon millions of crazy fans, almost suicidal in their devotion. These fans are camping outside London's Leicester Square ahead of the One Direction's movie, 'This is Us', premiere on Tuesday. 'This is Us' promises to show the real, unknown side of the five members of the band -- Niall Horan, Zayn Malik, Liam Payne, Harry Styles and Louis Tomlinson.

The band's every move -- both on and off-stage -- is tracked and discussed at length on social networking sites.

"There is only so much you can get across in terms of your personality, you know, social media and like 10-minute interviews you do with people," Harry said in a press conference, as quoted by Reuters.

"So I think ...(it's) a way for us to get across what we are like and what we are like with each other for the fans to see."

The five member band finished third in the British T.V. singing competition, 'The X-Factor' Season 7, that aired in 2010. But, soon shot to fame after they signed-up with Simon Cowell's Syco Records. One Direction rise as the most searched and followed boys band has been meteoric and phenomenal.

Morgan Spurlock has directed the One Direction's movie 'This is Us'. He said that the documentary film would show that the phenomenal rise of the band is due to their "down-to-earth personalities."

"Part of the reason I think they have been so successful with their fans is that they are so incredibly grounded and normal and that's what comes off in the movie, there's no air of superiority," Spurlock said.

According to Reuters, the film features footage from the concerts, life backstage as well as on the road clips. When asked whether the clips showing them with groupies or drugs had been edited out, the members of the band laughed.

"This is a family press conference," Harry said.

Zayn told Reuters in an interview that certain aspects of the fame took even them by surprise. "We never wanted to have the title 'celebrity,' we just want to be normal lads in a music band. We're not celebrities, we're just in a band."

One Direction's fans mainly consist of teenage girls and these girls form a major chunk of the 14 millions Twitter followers.

"Some of the girls are crazy," Spurlock said in an interview with Emma Jones of The Independent. "The boys have such a security apparatus around them constantly just to protect them. If they walk outside they will be mobbed, they will be chased. Their tour bus is chased down the street by hundreds of girls after the show."

'This is US' Movie Trailer