Tokyo usually has the most newest Technology around the world!
and as you know about the Persocoms, they
have a lot of exciting effects that fits with Tokyo's technology. ^__^
In the 1st episode, you saw Hideki wanted to buy one of the Persocoms, but he couldn't, and the reason that the Persocoms costs so much! so that helped in 2 ways: #1: to let Hideki find a mysteries Persocom. #2: shows that Tokyo is very expensive country.
Japanese people really love cute, small, and those exciting things!
Most of Japanese people, who are 18 years old like viewing adult sites XD! that's what the series says, but as I said, most not all, and I just tell from watching the anime series ^.^;