In the near future, technology has made a few leaps and bounds, and videophones and constant wireless internet access are available to everyone. However, it would seem that the government has been careless and a skilled hacker was able to break into the national information archive. Using the data held there he creates the Platonic Chain website for people to discover information about themselves and their friends. Words start to spread quickly that there is a site that enables you to look up anything. Coincidentally, three young girls, Hitomi, Rika, and Kanae, are able to access the site.
(Source: Anime News Network)
Note: The DVD version of Episode 16 was released with some minor variations compared to the regular TV broadcast
— Description from AniList community (anilist.co).
