SES in Japan: How to Spot a Body-Shop Before You Sign (From a Japanese Engineer)

You found a job in Japan. The company sponsors your visa, the salary looks okay, and the interview was surprisingly easy.

Then you arrive, and on day one you’re sent to work at another company’s office. Your manager is someone you’ve never met. Your “team” doesn’t know your name. Three months later, the project ends and you’re told to “wait at home” until the next one.

Welcome to SES.

Most Japanese engineers know exactly what SES is. But it’s rarely explained to people applying from overseas — which is a problem, because SES companies can sponsor work visas just like any other employer, and their job postings often look the same.

This article is the honest version.

What SES actually means

SES stands for System Engineering Service (システムエンジニアリングサービス). In practice, it means:

Your employer places you at a client company to work on the client’s project. The client pays your employer a monthly fee for your time. You are paid a salary by your employer.

Japanese engineers usually call this 客先常駐 (kyakusaki jōchū) — “stationed at the client’s site.”

Legally, SES is usually a quasi-mandate contract (準委任契約). The client is paying for your working hours, not a finished product.

How it compares to other “tech companies” in Japan

Type	Japanese term	What you actually do
Product company	自社開発 (jisha kaihatsu)	Build your own company’s product
Contract development	受託開発 (jutaku kaihatsu)	Build software for clients, usually at your own office
SIer	エスアイヤー	Large system integrators; design and manage big client systems, often outsourcing the building
SES	客先常駐	Placed at a client (often under an SIer) to add headcount

All four can call themselves an “IT company.” All four can sponsor an Engineer visa. The job posting often looks the same.

Why SES can be a bad deal

Not every SES job is terrible. But the structure creates problems you should understand before you sign.

1. Multi-layer subcontracting (多重下請け)

Big Japanese IT projects often flow down like this:

End client (bank, manufacturer, government)
  └─ Prime SIer
       └─ 2nd-tier company
            └─ 3rd-tier company
                 └─ Your SES employer → you

Every layer takes a margin. The deeper your employer sits in this chain (Japanese engineers call this 商流, shōryū, “the commercial flow”), the less of the client’s money reaches you — and the less say you have over the work.

2. You don’t choose your project

Your employer’s job is to keep you billable. If the only open slot is running manual tests on a legacy system in a language you’ve never touched, that may be where you go. Your career growth depends on which projects happen to be available.

3. The “bench” (待機)

When a project ends and there’s no next one, you’re on standby (待機, taiki). Some companies treat this well. Others pressure engineers to accept any project, or cut pay during standby.

Honne tip: Under Japan’s Labor Standards Act (Article 26), if you can’t work for reasons attributable to the employer, you’re entitled to a leave allowance of at least 60% of your average wage. If a company says “no project = no pay,” that’s a serious red flag.

4. Your formal evaluation comes from people who don’t see your work

You work at the client’s office, but your salary review is done by your employer — who rarely sees your day-to-day work. At weaker SES companies, raises depend more on how much the client pays for you than on how good you are. (The client team’s opinion still matters a lot — more on that below.)

5. Japanese level surprises

Many SES placements are with traditional Japanese companies where meetings, documents and chat are all in Japanese. A job posted as “English OK” can become “business Japanese required” once you’re assigned.

MARU’s honne: how SES engineers are actually seen on site

On past projects, I’ve worked alongside SES engineers on client-side teams. Here’s the honest picture.

You’re not an employee of the client, but you’re still held responsible for your work. The good news: the bar is clear. If you do what you’re asked, properly and on time, the client-side team notices — and that leads to good evaluations. And the more you take initiative beyond your assigned tasks, the more highly you’re rated.

One thing is non-negotiable, whether you’re an employee or SES: hō-ren-sō (報連相) — hōkoku (report), renraku (inform), sōdan (consult). Report progress before you’re asked. Flag problems early. Ask before you guess. In Japanese workplaces, an engineer who is technically strong but goes silent is trusted far less than one who communicates constantly.

Why does the client team’s opinion matter so much? Because in SES, the client decides whether to extend the contract for your placement. Even though your employer does your formal review, the client team’s impression of you is what keeps you on a good project.

Red flags in the job posting

You can often spot SES before the first interview. Look for these:

What you see	What it often means
Work location: “client sites in Tokyo” / 勤務地：顧客先 / プロジェクト先	You’ll be stationed at clients. The clearest signal.
“Various projects available” with no product named	They’re selling your time, not building something.
Tech stack lists 15+ languages and frameworks	They’ll place you wherever there’s demand.
“No experience needed” + visa sponsorship + many openings	Volume hiring to fill client headcount.
Company website mentions SES事業, 技術者派遣, or エンジニア派遣	That’s the core business.
The company holds a worker dispatch license (労働者派遣事業許可, number like 派13-XXXXXX)	Not proof of SES, but a strong hint they place staff at other companies.
Very fast offer after a short, non-technical interview	They need bodies, not a specific skill.

How to check the dispatch license: Japan’s Ministry of Health, Labour and Welfare runs a public search called 人材サービス総合サイト (Human Resources Services General Site). Search the company name to see whether it holds a dispatch license.

Questions to ask in the interview

If you’re not sure, ask directly. A good company will answer clearly. A company that dodges these questions is telling you something.

“Will I work at your office or at a client’s site?”
“What percentage of your engineers work at client sites?”
“For my first project, who is the end client, and what tier is your company in the chain?” (商流は何次ですか？)
“What happens to my salary if a project ends and there’s no next project yet?”
“Who evaluates my performance, and how is my salary review decided?”
“Can I decline a project?”
“What language are meetings and documents in at the client site?”

MARU’s honne: what the interviewer is really looking for

From the hiring side, what decides the outcome is the same as any job interview in Japan: can you clearly explain what you’re good at as an engineer, and how you’ll use it in this role? Be specific — not “I know AWS,” but “I built and ran the CI/CD pipeline for a service with X users, and I can do the same for your team.” If you can make that case concretely, you’re in good shape.

Is SES ever a good idea?

Honestly, sometimes — yes.

As a way into Japan. If your options are limited, an SES offer that sponsors your visa can still get you into Japan. A residence card and Japanese work history make your next job search much easier.
Good SES companies exist. Some are close to the end client (1st or 2nd tier), pay fairly, protect engineers during standby, and let you choose projects.
Variety. You’ll see many companies and tech stacks quickly.

The key is to go in with your eyes open, and to have a plan: for example, “one to two years in SES, build Japanese and experience, then move to a product company.”

When you change jobs, your Engineer visa generally stays valid as long as your new work fits the same visa category — but check the rules for your situation and file the required notification with immigration within 14 days of changing employers.

Summary

SES = you are placed at client companies. Your employer sells your hours.
The problems come from multi-layer subcontracting, no project choice, standby risk, and evaluation by people who don’t see your work.
Spot it from the posting: “client sites”, vague projects, huge tech lists, dispatch license.
Ask the seven questions. Clear answers are a good sign.
SES can be a stepping stone — just don’t let it become your whole career by accident.

This article is general information, not legal or immigration advice. For your specific situation, consult your employer, a licensed gyoseishoshi, or the Immigration Services Agency of Japan.

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