It is one of the world’s largest underworld organisations, explicitly involved with extortion, arms dealing, drug trafficking, extreme violence and online pornography.
The deadly yakuza gang has hosted the yearly extravaganza close to its fortified headquarters in the city of Kobe since 2013. Youngsters who arrive in costume are given sweets, gifts and money.
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But worried police have now submitted a bill to the region’s Hyogo Prefectural Assembly proposing members of Yamaguchi-gumi be banned from showering such presents on anyone under the age of 18.
It comes after city officials grew increasingly concerned the October parties were being used as a way to both falsely soften the image of the ruthless mob and attract young members into its 9,000-strong ranks.
If passed, the bill would also mean gang members were not allowed to let children on to their premises or make contact with them in any other way, according to the Asahi Shimbun newspaper.
Anyone breaking the new law would face up to six months in prison or a fine of 500,000 yen (£3,700) .
Although similar events were cancelled last year and in 2015 on public safety grounds, local education authorities have been reluctant to warn schoolchildren not to attend – out of an apparent consideration for students whose parents have links with the mob.