Studio Trophis also have also produced a downloadable audio drama called "The Grey Tower". It can also be downloaded for free from their website.
The Grey Tower is a prequel to The White Chamber, althought it is better to have played the game first, as there are spoilers.
At the beginning of March, Studio Trophis released a new version of the game that included English voice acting and added four new endings to the game and the option of changing the language of the text.
English version of the game is available as free download from Studio Trophis web pages (http://www.studiotrophis.com/, about 300 MB).