Most residents of Tokyo's pulsing Shinjuku ward, home to the busiest railway station in the world, are of the Homo sapiens variety.

Shinjuku has a population density of about 17,000 people per square kilometre but undeterred by this it has granted citizenship to a new resident, who only goes by one name - Godzilla.

Godzilla's citizenship certificate

Name: Godzilla

Address: Shinjuku-ku, Kabuki-cho, 1-19-1

Date of birth: April 9, 1954

Reason for special residency: Promoting the entertainment of and watching over the Kabuki-cho neighborhood and drawing visitors from around the globe

Previous visits to Shinjuku Ward: 3 times; Godzilla (1984), Godzilla vs King Ghidorah (1991), Godzilla 2000 Millennium (1999)

What can Godzilla do in Shinjuku?

While Godzilla's genus is uncertain (thought to be a cross between a gorilla and a whale) in Shinjuku he will find much to do and see. Apart from Tokyo's flagship station, it has the capital's city hall, a high concentration of skyscrapers, Tokyo's best known red light district as well as some quieter residential areas as his potential stomping ground.

Godzilla at play in Tokyo. Photo taken from BBC

The city describes itself like this on its website: "A town of remarkable growth as a new downtown district, a town with many cultural assets and traditional events, a town where many people lead active lives together… This is Shinjuku!" It says urbanisation began a while back in 1636.

It's obviously a PR move by Japan and Shinjuku - but ever since Godzilla first appeared in Ishiro Honda's 1954 film and then a series of tokukatsu (live action) films in Japan, the character has remained important in Japanese pop culture and history.

Godzilla's job will be tourism ambassador

To mark the arrival of its newest resident, the Shinjuku City Office distributed 3,000 copies of Godzilla's certificate to delighted fans on Saturday.

Godzilla was also appointed Shinjuku's tourism ambassador earlier in April. Photo: AP

A 2014 Hollywood remake of the original Godzilla film topped both the US and UK box offices. Photo: AP

A replica of Japan's undisputed "King of Monsters" was also placed on top of the district's iconic Toho building. The Japanese film company will release a new Godzilla film in 2016, following the success of a 2014 Hollywood remake by British director Gareth Edwards.

Godzilla attended an awards ceremony in April, where he was presented with a sash from Shinjuku mayor, Kenichi Yoshizumi.

Many ward residents and Japanese alike welcomed Tokyo's undisputed "King of Monsters".

"Congrats,  big guy! It's about time," said a Shibuya resident on Twitter.

Others showed generosity of spirit. One Tokyo Twitter user remarked: "Welcome to Tokyo! We forgive you for destroying our city previously."

Others even expressed hope for Japan's newest resident to lend a hand in regional geo-political disputes.