Toshiro Muto, CEO of Tokyo 2020 Organizing Committee of Olympic and Paralympic games, and Akira Shimazu, CEO of the Rugby World Cup 2019 Organizing Committee. Photo: Issei Kato/Reuters

Despite several high-profile gaffes in their 2020 Olympic preparations, Tokyo 2020 organisers reckon choosing the Games mascots will be child's play – so much so they're leaving the decision to schoolkids.

Japanese organisers announced Monday that the official 2020 mascots would be decided by a nationwide competition, in which members of the public will submit designs before elementary schoolchildren across the country select winners from a shortlist.

Budding designers have a two-week window from August 1-14 to submit entries, after which a mascot panel will compile a shortlist in December.

Japanese schoolchildren, who could have a better handle on the squidgy mascots than organisers who have hitherto bungled the rollout of the Olympic stadium and official logo, will finish voting on the shortlist in January.

The winning designs will be announced in March, with the mascots to be given official names by August 2018.

Mascots – often referred to in Japanese as 'yuru-kyara' (soft characters) – are big business in Japan and have become part of the cultural landscape.

The market for characters like Kumamon, a giant black bear with red cheeks which represents Kumamoto prefecture, and his bitter rival Funassyi – a hyperactive 'pear fairy' with a love for heavy metal – is an eye-watering $30 billion a year, with mascots adorning everything from key-chains to planes.

Tokyo organisers are battling to rein in runaway costs for the 2020 Olympics which have cast a shadow over preparations.

The city's bid committee estimated costs of $7 billion and projected an economic windfall in excess of $25 billion.

But a panel of experts have warned the overall budget could exceed that without drastic cuts.

That warning came after Japanese Prime Minister Shinzo Abe tore up the original plans for the Olympic stadium over soaring costs and organisers scrapped the first design for the 2020 Games logo after accusations of plagiarism.