?Bollywood star couple Alia Bhatt and Ranbir Kapoor on Sunday said "Brahmastra Part One: Shiva" is special in more than one way as the movie gave them "Kesariya", a song that symbolises their off-screen relationship.

Bhatt and Kapoor, who tied the knot in April, are set to share screen space for the first time in the fantasy adventure film, directed by Ayan Mukerji.

On Sunday, the makers released the full version of "Kesariya", the song which was teased the day before the pair got married on April 14.

In a Q&A session on Instagram ahead of the track's launch, Kapoor said he and Bhatt would often wonder about having a 'couple song'.?

"Alia and I have spoken about this 'What is our song?" he said.

To which Bhatt added, it was "weird" they didn't have their song for the longest time.?

"Now we have 'Kesariya' and it's special," the actor, who announced her pregnancy last month, added.

Kapoor, whose last film release was 2018's "Sanju", said music composer Pritam had come up with many versions of "Kesariya", sung by Arijit Singh. Amitabh Bhattacharya has penned the lyrics.

"We had so many new options... I don't remember the last time there was so much anticipation for a song. We feel blessed, lucky, that we are in this moment," he said.

Mukerji was also part of the live session and the director said he hadn't planned to launch the film's music with "Kesariya". The track was released in Hindi, Tamil, Telugu, Kannada and Malayalam.

"When we had planned the journey of our music launch, we wanted to put out our 'Shiva' unit, which will probably be the song that'll come out next. But I realised that if we don't drop 'Kesariya', we will get too many abuses. There was just too much anticipation," he said.

The music video of the song was shot in Varanasi, including the Kashi Vishwanath Temple.

Shooting at the iconic temple was one of the main highlights of the video, added the director.

"I wanted to get to the temple but didn't know if it would be possible. Finally, we pulled it off! We spoke to the right people, told them we would be very respectful about shooting there. They understood what it meant to us. It was a crazy day of shooting, managing the crowd, somehow not disturbing the 'darshan' and getting what we needed," Mukerji said.

"Brahmastra Part One: Shiva", which has been in the works for a decade, is set to be released on September 9 this year.

When asked by a fan about the long wait for the film's release, the director said the team wanted to put their best foot forward.

"As people start seeing more footage of our film, I hope this will get clear. It is an extremely ambitious, new and original project. The kind of quality we wanted to create with this film, it needed that time.?

"The visual effects, planning, action, post production, etc. It has been my effort — and that of everyone on the film — that we have to hit that standard with 'Brahmastra', and we didn't want to compromise that," Mukerji said.

The film marks the third collaboration between Kapoor and Mukerji, following "Wake Up Sid!" and "Yeh Jawaani Hai Deewani".

Calling the filmmaker a "genius", Kapoor said he has immense faith in Mukerji's vision.

"I'm a big cheerleader of his talent and what he will achieve in the industry," he added.

Produced by Star Studios, Dharma Productions, Prime Focus, and Starlight Pictures, "Brahmastra Part One: Shiva" also stars Amitabh Bachchan, Mouni Roy and Nagarjuna Akkineni.

[With Inputs From PTI]