---
id: "lib-2026-11-06-a-four-day-week-at-full-pay-through-ai-efficiency"
type: "library"
title: "A four-day week at full pay through AI efficiency, and staff did not cheer (「給与維持の週休3日制」AI効率化で実現　しかし社員が喜ばず……なぜ？)"
lang: "JA"
org: "ITmedia NEWS / SpiralAI"
source_type: "Article"
date: "2026-11-06"
week: "2026-W45"
url: "https://nosov.ai/library/lib-2026-11-06-a-four-day-week-at-full-pay-through-ai-efficiency/"
original_url: "https://www.itmedia.co.jp/news/article/2611/06/2000002867/"
tier: "B"
tier_name: "Useful, limited"
tier_reason: "ITmedia NEWS interview with the CEO of SpiralAI on a four-day week introduced to force AI use; first-hand detail on staff reaction, but every outcome is the CEO's own impression and the company has no quantitative data yet."
summary_basis: "full-text"
original_minutes: "7"
tags: ["future of work", "business transformation", "working time", "change management"]
---

# A four-day week at full pay through AI efficiency, and staff did not cheer (「給与維持の週休3日制」AI効率化で実現　しかし社員が喜ばず……なぜ？)

Tier B (Useful, limited): ITmedia NEWS interview with the CEO of SpiralAI on a four-day week introduced to force AI use; first-hand detail on staff reaction, but every outcome is the CEO's own impression and the company has no quantitative data yet.

Summary based on the full text.

## In short

ITmedia NEWS (6 November 2026) interviews Yuichi Sasaki, CEO of SpiralAI, a Tokyo generative-AI start-up founded in March 2023. In June 2026 it added Friday as a day off for about 20 full-time staff without cutting pay, reducing weekly hours by about 20%, explicitly to make AI use mandatory rather than optional. Nobody welcomed the announcement: juniors looked anxious and a director challenged whether management could really take responsibility for deadlines. The routine settled in about a month, and the CEO says efficiency has risen by more than 20%, though there is no data.

## Key numbers

- ~20%: cut in scheduled weekly working hours from June 2026, at unchanged pay and daily hours
- ~20: full-time staff covered by the four-day week
- ~3 months to ~1 month: time to build a small app: a planner plus several engineers before, one planner with AI now
- 2 weeks / 1 month: period some staff were "afraid of Fridays" / time until the new cycle settled

## What it reports

- Scope: about 20 full-time staff, average age early thirties, no remote work. Daily hours unchanged; weekly scheduled hours down about 20%.
- Motive: the CEO saw in consulting that people resist changing how they work; cutting hours was chosen as a "drastic remedy" so that everyone must become 20% more efficient with AI.
- Reaction: "not a single person said 'great'". Staff worried about keeping client deadlines and quality; clients barely asked about the change.
- Some staff were "afraid of Fridays" for the first two weeks; after about a month work ran as before.
- Small applications that took a planner and several engineers about three months are now built by one planner with AI in about a month. In Slack, staff's AI agents sometimes talk to each other to add features or check specifications.
- No quantitative productivity data yet; no major problems with client deadlines or quality reported. The CEO's own sense is "well over 20%".
- The change is treated as one-way: reducing holidays again could be an unfavourable change to working conditions.
- The CEO thinks it suits firms with staff who have ideas to prove; where work is mainly following instructions, it may only add a day off. He says a 10-20% efficiency gain from uses such as AI-drafted email is possible in any industry.

## How they got it

A single interview with the CEO by a freelance reporter, across three web pages.

## Limits

- All outcomes come from the CEO; no staff interviews or output data.
- Small, young start-up whose product is AI; transfer to other firms is uncertain.
- About four months of experience at the time of the interview.

## Why it matters for companies

Most firms leave AI gains to individuals, who often absorb or hide them. SpiralAI took the opposite route: cut the hours first and let the time constraint force the change. The useful detail is the reaction: staff worried about accountability for deadlines, not about losing a working day. Any firm trying this needs a plan for deadline ownership and should treat the change as hard to reverse.

## Key passages in translation

> みんな喜んでくれると思ったら、誰一人として『やった』と言わなかった

I thought everyone would be pleased, but not a single person said "great".

> 働く時間が20％減るので、全員が作業を20％効率化しないといけない。AIを使えたらいい、ではなく、使わないといけない状態にする狙いがあった

Working time falls by 20%, so everyone has to make their work 20% more efficient. The aim was to move from "it would be nice to use AI" to a state where you have to use it.

> 生産性の向上を裏付ける定量的なデータはまだないものの、取引先への納期やサービスの品質に、制度導入による大きな支障は出ていない。

There is no quantitative data yet to back up the productivity gain, but the system has not caused major problems for client deadlines or service quality.

Original: https://www.itmedia.co.jp/news/article/2611/06/2000002867/