Previously

In Part 2: The Great ChatGPT Struggle, I recounted my epic battle with ChatGPT. Endless copy-pasting, code that broke every time I fixed something, and an AI that forgot previous context. For someone with zero programming experience, the workflow of "AI writes code and displays it in chat" was pure hell.

Just as I was about to give up, I discovered a certain tool.

Claude Code — What Made It Different

One day, I spotted the words "Claude Code" on my X timeline.

My first thought was, "Probably just another AI chatbot." I'd already been burned badly by ChatGPT. My expectations were near zero.

But as I read the description, one thing stood out as a game-changer.

The Critical Difference Between ChatGPT and Claude Code
ChatGPT "displays code in the chat window." You copy it and paste it into the correct file yourself.

Claude Code "reads and writes files directly on your PC." No copy-pasting needed. The AI already knows where your files are.

It might be hard for experienced programmers to appreciate how revolutionary this was.

But for a complete beginner, it was a night-and-day difference.

The First Experience — Shock

I installed Claude Code and opened the terminal.

Honestly, seeing the terminal (that black screen) was a little intimidating. But I took the plunge and started talking to it in Japanese.

👨
I have a GAS file for attendance management that I partially built with ChatGPT. Can you take a look?
🟠
Let me check the file. …Done. Here's the current structure. I found a few issues — want me to fix them?
👨
Wait, you already read it? And you can fix it too?
🟠
Yes, I can edit the file directly. Shall I go ahead and fix it?

When I said "take a look," it actually went and looked. When I said "fix it," the file actually changed.

No copy-pasting. No switching between browser and editor. No mixing up files.

0
Copy-pastes
0
Wrong file edits
All of it
Code the AI is aware of

Freedom from Copy-Paste Hell

With ChatGPT, a single fix took 5 minutes. Read the code, copy it, open the file, paste it, save, run, check the error, go back to ChatGPT…

With Claude Code, a single "fix it" is all it takes.

The ChatGPT Era

Code appears → Copy → Switch to editor → Select all → Paste → Save → Run → Error → Back to chat → Copy error message → Paste → New code appears → Start over

Claude Code

"There's a bug here" → Fixed

This is not an exaggeration. That's literally how it works.

The Comfort of "It Remembers"

Another thing that made ChatGPT hellish — the context-forgetting problem.

Claude Code reads the files in your project directly. So it never forgets the name of "that function I just wrote." Because it's right there in the file.

With ChatGPT, all it had to work with was the conversation text I'd sent. But with Claude Code, the source code itself is the memory. No matter how long the conversation gets, it can read the files to understand the current state.

👨
I want to pick up where I left off yesterday. How far did we get?
🟠
I've checked the files. Here's the current progress… (accurately describes the file structure and feature list)
👨
(This thing… actually gets it…!)

Development Speed: 10x Faster

This isn't just a feeling — it's a fact.

A feature that took a full week during the ChatGPT era was completed in half a day with Claude Code. Eliminating the copy-paste overhead was part of it, but more importantly, the fixes were accurate.

The whack-a-mole of fixing A only to break B dropped dramatically. Because Claude Code sees the entire file, it understands the ripple effects of every change.

What Claude Code Means for Non-Programmers
The important thing is that I didn't suddenly become able to "write" code. I still can't write code from scratch. But if I explain "what I want to do" in plain language, the AI writes the code, saves it to the file, and fixes errors for me. All I needed was a vision of "what I want to build."

And Then Development Took Off

During the ChatGPT era, just getting a basic attendance tracker to work was all I could manage.

After discovering Claude Code, features started piling up one after another. Calendar integration, automatic tallying, PDF invoice generation…

"Could other tutors actually use this too?"

That thought first crossed my mind right around this time.

Next Time

Part 4: The Birth of Kagemusha — The moment a personal tool becomes a "product." The meaning behind the name "Kagemusha" and the first steps toward turning it into a real product.

Still managing tutor attendance manually?

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