Video has appeared online showing a man who appears to be New Zealander shouting aggressively at a Japanese man in Tokyo.
"When I went to Shibuya wearing a Halloween Minion [costume] I was suddenly hit by a foreigner," a Twitter post containing the video says in Japanese.
The footage was shared on Sunday and has been viewed almost 100,000 times.
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In it, a shirtless man is seen yelling aggressively at a Japanese man, with police running to keep the two apart.
"Let's go, let's go," the shirtless man can be heard yelling in what sounds like a Kiwi accent.
"You f***ing dork.
The person filming the altercation can be heard saying he is friends with the Japanese man and is filming to have "evidence".
There was some speculation as to the man's nationality in comments on the post.
"This guy is from New Zealand... Sore loser." one person wrote in English.
"He sounds more Australian to me," another person wrote.
In the original Twitter post, the uploader says only part of the altercation was filmed, and it is not clear whether anyone involved was arrested.
Shibuya, an entertainment and shopping district famous for its massive zebra crossing, was brimming with people dressed up in Halloween costumes and out for a good time over the weekend, according to The Japan Times.
They were met with a large police presence after revellers last year ran amok and overturned a small truck and damaged other property.
In order to avoid a repeat performance, a drinking ban was also in effect from 6pm to 5am on October 25 to 27.
The drinking ban will also be in place on October 31.