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August 3, 2025

How Japanese Code Reviews Differ from Silicon Valley — And Why It Matters

I didn’t expect it, but my first pull request in a Japanese engineering team took four days to merge.

Abhinav

3 min read

Not because I broke anything. Not because I was new.

But because they were reading it like a legal contract.

Meanwhile, back in Silicon Valley, I'd been merging PRs with three approvals and a thumbs-up emoji in under an hour.

Two different worlds. Two different philosophies.

Same job: writing and reviewing code.

Over time, I realized the Japanese approach isn't slow — it's deliberate. They review code like it'll be running five years from now, in a system they'll still be responsible for.

And it kind of changed how I think about engineering.

1. Silicon Valley Moves Fast. Japan Moves with Care.

In the Valley, most code reviews feel like a pit stop.

You open a PR, write a summary, tag two people, and wait for comments like:

  • "LGTM"
  • "minor nit, feel free to ignore"
  • "🚀"

It's efficient. You move quickly. Mistakes get fixed later.

In Japan, things are… slower. On purpose.

Pull requests are read carefully. Reviewers might clone the branch, test it themselves, and ask deep questions about architecture, not just logic.

It's not unusual to get something like:

- const timeout = 3000;
+ const timeout = 3000; // hardcoded timeout — should we extract this?

// Comment:
"This might be better as a config or constant.
If the business logic changes, hardcoded values could be risky later."

Not flashy. But solid.

2. In Japan, Code Review Is Also Architecture Review

In most Valley teams, design discussions happen before the PR — maybe on a whiteboard or a Notion doc.

Once the PR is open, it's more about:

  • "Did you follow the design?"
  • "Is this safe to deploy?"

But in Japanese teams, the PR is part of the design conversation.

You might write code that technically works, and get a comment like:

"Should this class be aware of payment logic? It feels like we're mixing domains."

They care a lot about separation of concerns — even if it means rewriting working code.

Here's a simplified UML-like sketch one reviewer sent me once:

+--------------+           +---------------+
|  RideOrder   | --------> |   Payment     |
+--------------+           +---------------+
| - rider      |           | - method      |
| - destination|           | - currency    |
| - status     |           | - taxPolicy() |
+--------------+           +---------------+

Their question was:

"Should RideOrder really know how tax policy works?"

It's not nitpicking. It's how they keep their systems clean — and future-proof.

3. Reviews Are Slow Because They're Also Teaching Moments

This is something I wish more teams did.

In Silicon Valley, junior devs are expected to learn fast. If you make a mistake, someone might fix it silently, leave a short comment, or link to Stack Overflow.

In Japan, reviewers take time to explain — in a calm, friendly way.

You might get a comment like:

- return !!(flags & 0x2);
+ return isEligibleFlagEnabled(flags);

// Comment:
"Bitwise operations are a bit obscure for newcomers.
This helper function makes the code easier to read and test.
Let’s also document what 0x2 represents."

You don't just fix your code. You understand why it needs fixing.

Even for tiny details, the intent is to help the next developer write better code — not just patch bugs.

4. Criticism Is Quiet. But It's There.

This one took me time to get used to.

In the Valley, it's totally okay to say:

  • "This logic is wrong"
  • "You're missing a check here"
  • "We should refactor this"

In Japan, that level of directness is rare — at least in a public thread.

If a reviewer thinks your design is broken, they'll probably message you privately or suggest a call. They won't write an essay in the comments tearing your logic apart.

But they will suggest alternatives carefully.

You might read a comment that says:

"This works well, but maybe we can explore another approach that keeps things loosely coupled?"

Which roughly translates to:

"This isn't ideal, let's not ship it yet."

It's subtle. Respectful. But crystal clear if you know what to listen for.

5. Japanese Engineers Write Code Like It'll Live Forever

The biggest cultural difference I noticed?

In the Valley, code is often written to be replaced. In Japan, it's written to be maintained.

That's why you'll see things like:

  • Avoiding clever one-liners
  • Adding comments that seem "too obvious"
  • Defensive programming even in stable code

Example:

// Quick version (common in Valley):
const isAdmin = user?.roles?.includes("admin");

// Japanese-style:
if (!user || !Array.isArray(user.roles)) return false;
return user.roles.includes("admin");

It's a bit longer, sure. But it survives edge cases, bad data, and future refactors without breaking silently.

So… Who's Right?

Honestly? Both.

Silicon Valley is great at iteration. Japanese teams are great at stability.

One builds fast, breaks, and learns. The other builds carefully, avoids breakage, and lasts.

But here's what I took away from the Japanese approach — and what I try to apply no matter where I work:

  • Review like the system matters.
  • Leave comments that teach, not just critique.
  • Think five years ahead — not just one sprint ahead.
  • Be kind. Be patient. Be intentional.

Because in the end, code is read more than it's written.

And Japanese teams? They review like they know that better than anyone.