Usually when things happen this way it means that facts changed in some way. Either they presumed until today that some sale or financing deal would come through, or their investors met and decided they had had enough.

Yep. I've seen this happen to another startup. They leased a massive (for them) office space only to shut down a few months later after a funding round fell through horribly.

A few months later is a lot different than 4 days later.

Big office deals take a long time to start, and have inertia once they're going. I can easily see someone starting a moderately speculative office expansion project and then getting distracted with fundraising, only to have everything fall apart at the same time, many months later.

Said another way: given the number of liabilities at a company that has taken hundreds of millions in funding and is flying low over the ground, a lease is probably not you biggest concern.

It's very traditional. The second you show that you're significantly scaling back you raise questions about whether you're a going concern. They could have canned the japanese office much earlier but then it's possible investors would say 'Hey, we thought the plan was to build strong links with Mitsubishi to prime for an acquisition for an exit, what's the plan now'. So the only real option is to push aggressively and hope it works out.

Fundraising might have fell through at last moment. Some major customer/partnership might've pulled the deal at the last moment. This all happens at startup level cashflow is tight. And all the investors thought there is no way this business with make sense based on the data they might have had on their hands. So they pulled the plug