Offices were closed on every Friday of August 2019 and full-time staff were given "special leave", which was paid.
Meetings were restricted to a maximum of 30 minutes and online discussions were encouraged as an alternative to face-to-face.
Japan has some of the longest working hours in the world.
A 2017 survey suggested nearly a quarter of Japanese companies had employees working more than 80 hours overtime a month, often unpaid.
Microsoft's Work Life Choice Challenge 2019 Summer experiment was popular with 92% of the staff it surveyed after the event.
During the month-long trial, electricity consumption had been reduced by 23% and paper printing by 59% compared with August 2018, Microsoft said.
Microsoft Japan said sales had been boosted by nearly 40% during an experiment in which staff worked a four-day week on full pay.
Last modified on Wednesday, 06 November 2019 14:29