“Wait, it’s connected that far?” — Behind a financial system was a massive team effort.

A System Cannot Run Alone.

Every Server Has a Role

Some time ago, I was involved in supporting the development of a financial system and helped introduce a system used in London into Japan.

One thing left a strong impression on me.

I realized that connecting systems and getting people to work together are, fundamentally, very similar.

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The London system was not simply one huge program.

It was built by combining many servers, each with its own specific role.

One server received data. Another processed that data. Then another server passed the processed results to the next system.

Each server was simply performing its own role.

But that alone does not create a system.

Only when each component follows the defined rules and connects properly can the entire system begin to operate as one financial system.

Being Connected Is Not Enough

This is where system integration becomes difficult.

It is not enough to simply connect two systems.

What data should be transferred?

When should it be transferred?

In what format?

What happens if an error occurs?

Which system is the source of truth?

Every connection has its own rules.

If even one of those rules does not match, the data cannot be transferred correctly.

And when data cannot flow properly, the individual systems may still be working perfectly—but the overall system will not function as one integrated system.

That is the difficult part of system integration.

Even within a single financial system, a large number of servers need to work together.

And the real complexity begins beyond that.

A Financial System Cannot Be Completed Internally

A financial system does not operate in isolation.

It needs to connect with various surrounding systems, such as internal web systems, notification systems, payment systems, and many others.

And beyond those systems are external systems.

This makes things even more complicated.

External systems are not managed by us.

Each one is managed by a different company, with its own circumstances, priorities, rules, and constraints.

That means changing our own system is not always enough to solve a problem.

“Could you make a change to this part?”

“Could you align the data format with ours?”

“Would it be possible to complete this by this date?”

We need to work with each company, coordinate specifications and schedules, and gradually align all the connection points.

Systems Connected Like a Pyramid

When you look at the entire picture, it almost looks like a pyramid.

One system connects to several other systems.

Those systems connect to even more systems.

And beyond them are systems managed by other companies.

Only when each individual connection works correctly can the entire structure operate.

That is why the most difficult part of a project is not simply building our own system.

It is making sure the entire ecosystem—including surrounding systems—works together.

Who needs to do what, and by when?

Where are the dependencies?

Where could problems occur?

We need to organize all of this, communicate with the stakeholders, and control the overall picture.

I believe that is one of the most important responsibilities in project management.

The Essence of System Integration Is Human Collaboration

Looking back, I realized that system integration is not simply an IT technology challenge.

Server to server.

System to system.

Company to company.

And ultimately, person to person.

Each participant performs their own role, aligns with the rules, understands the circumstances of others, and gradually connects their part to the bigger picture.

That is exactly what it means to work together.

Through the collaboration of many people and many companies, complex systems are connected together—and that is how Japan’s financial systems operate.

I was fortunate to play a small part in that larger ecosystem.

When I think about it that way, the meaning of each individual task begins to look very different.

And I believe the same principle applies to DX today.

AI. IoT. Cloud. Data.

No matter how advanced the technology is, simply introducing new technology does not complete a digital transformation.

Technology and technology.

People and people.

Organization and organization.

Company and company.

The real challenge is connecting all of them and making them work together as one system.

Perhaps the essence of DX is not simply building systems, but building an ecosystem where people and systems can connect and create value together.

Today, I continue my work while appreciating the importance of being one small part of such a large and interconnected ecosystem.

I can do it! Tomorrow, I’ll take the next step.