.htaccess rewrite rules for multiple sites - regex

Question

Scenario
I have 3 domain names:
www.hellokitty.com
www.keroro.com
www.doraemon.com
I want to host all of them in one web hosting with the following directories:
./htdocs/hellokitty.com/
./htdocs/keroro.com/
./htdocs/doraemon.com/
All of them are linked to the same hosting server with A record.
However, my hosting do not support virtual host.
I need .htaccess files to rewrite the URLs
So, I tried in this way:
RewriteEngine on
RewriteCond %{HTTP_HOST} ^(www.)?hellokitty.com$ [NC]
RewriteCond %{REQUEST_URI} !^/hellokitty\.com/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /hellokitty\.com/$1
RewriteCond %{HTTP_HOST} ^(www.)?hellokitty.com$ [NC]
RewriteRule ^(/)?$ hellokitty.com/index.php [L]
RewriteCond %{HTTP_HOST} ^(www.)?keroro.com$ [NC]
RewriteCond %{REQUEST_URI} !^/keroro\.com/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /keroro\.com/$1
RewriteCond %{HTTP_HOST} ^(www.)?keroro.com$ [NC]
RewriteRule ^(/)?$ keroro.com/index.php [L]
RewriteCond %{HTTP_HOST} ^(www.)?doraemon.com$ [NC]
RewriteCond %{REQUEST_URI} !^/doraemon\.com/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /doraemon\.com/$1
RewriteCond %{HTTP_HOST} ^(www.)?doraemon.com$ [NC]
RewriteRule ^(/)?$ doraemon.com/index.php [L]
Thus, if I go to www.hellokitty.com, it rewrites to ./htdocs/hellokitty.com/ internally.
Problem
If I go to www.hellokitty.com/hellokitty.com/
Or, if I go to www.hellokitty.com/keroro.com/, it still works
So, my problem is that how to prevent the client direct access the above real URLs and show a 404 error to them?

Answer 1

Insert this rule just below RewriteEngine On line:
RewriteCond %{THE_REQUEST} /(hellokitty|keroro)\.com [NC]
RewriteRule ^ - [F]