Since I was going to work with WordPress, I decided to try it out on my usual Windows PC.
Now, when I looked into how to run WordPress, it seems that WordPress works with PHP, MySQL, and Apache, and on a Windows PC, you can install a "XAMPP" that is a collection of software necessary to run web applications and use it to run WordPress.
So, I decided to install XAMPP first.
You can download the installer from the "XAMPP for Windows" page on the Japanese page (http://www.apachefriends.org/jp/xampp.html) of XAMPP. On the same page, there are instructions on how to install it, so read it while downloading.
Once the installer is downloaded, run it and click Start Installation. It's English, but basically it's good to just say "Next".
So, after the installation is completed, the XAMPP control panel will start, so press the "Start" button for Apache and MySQL to start it (when the startup is complete, the text background in the "Module" field will be green).

Once you've made it this far, launch your browser and type "http://localhost/" in the address field, and the following screen should appear.

Next, set phpMyAdmin. At the bottom left of the screen, there is "phpMyAdmin", so click here.

Now, let's create a DB to use in WordPress.
If you put the appropriate DB name (I tried "wordpress" for the time being) in the input field and press the "Create" button, the DB will be created. Of course, the contents are still empty.

Once you've created your DB, it's time to install WordPress.
Extract the zip file you downloaded from your WordPress Japanese site. Then you will have a directory called "wordpress", which you can put in the whole XAMPP htdocs (by default, it will probably be "C:\xampp\htdocs").
Once you've done that, access "http://localhost/wordpress/" in your browser.

There are some errors, but this is normal.
The button "Create configuration file" is displayed, so press it.

The button says "Let's get started," so press it.
Then, the following screen will be displayed, so set the database name to the DB name you set earlier in phpMyAdmin, set the username to "root", leave the password blank, and press "Submit".

The following screen will be displayed. It looks like you're ready, so press "Run Install".

So, when I thought that the installation would start, it seems that I still need to enter various things, and the following screen will appear.

It seems that the information set here can be changed later. For now, give it a suitable title, enter your admin password and email address, and press "Install WordPress".

I was apologized for being able to install it easily, but this is the end of the installation. It's certainly easy to install, isn't it?
Oops, by the way, I haven't set the root password for MySQL yet. Let's set it up here.
Open the XAMPP settings screen in your browser and click "Security" in the left menu to see the following screen.
It is true that you are told that there is no root password for MySQL.

So, if you click on the URL "http://localhost/security/xamppsecurity.php" in the middle of the screen, you will see the root password setting screen, so you can set it there.

Enter a new password, check the box, and click "I have changed your password" to change your password.
So, if you change the root password of MySQL, you will need to set the root password even if you are a WordPress user, so open the "wp-config.php" of the WordPress installation directory (C:\xampp\htdocs\wordpress) in a text editor and select "DB_PASSWORD Enter the password you set earlier.