Meta chief Mark Zuckerberg was in Japan on Monday on a mini-Asia tour involving sword-making, mixed-reality headsets in Seoul and reportedly also lavish pre-wedding celebrations for an Indian multi-billionaire Mukesh Ambani's son, Anant Ambani.

Zuckerberg posted footage on Sunday on social media of a "special afternoon learning about making katanas" with a sword master, including of him hammering molten metal and swinging a blade.