During an interview with Latino Review, Guillermo del Toro provided an update on the television live-action adaptation of Naoki Urasawa's Monster.
Del Toro has mentioned the series a lot in the past. The plans to adapt the series started back in April 2013. During the fourth annual Hero Complex Film Festival he spoke more about the project:
Monster is currently available in manga form by Viz Media and in anime form by Siren Visual over in Australia. There are currently no plans to have the series licensed in the United Kingdom nor the United States.

You can read more about the interview here, it's main focus is Crimson Peak which will soon hit cinemasCan you give me an update on the status of 'Monster' project for HBO?
Guillermo del Toro: We are going to other companies to pitch it and see if anyone wants to do it. We finished writing a couple of the episodes, and so we have a sampler. We're going to go and see what happens with that, but very likely that will happen somewhere next year.
It's still at HBO?
Guillermo del Toro: No, it's out of HBO, and now we're going to take it to other places but it's not active active until we pitch it.
Del Toro has mentioned the series a lot in the past. The plans to adapt the series started back in April 2013. During the fourth annual Hero Complex Film Festival he spoke more about the project:
Source: Crunchyroll“You cannot compress ‘Monster’ into a feature,” del Toro said of the project he is co-writing with “Doctor Who” and “Sherlock” writer Steven Thompson. “‘Monster’ is almost like Chekhovian, it has all these little characters that are incredibly smart and delineated. Each of them has an arc and if you follow all of them, at the end of the last book you will be satisfied.”
At the time, in order to get permission, he needed to agree to submit an outline of every episode of the theoretical first season to Urasawa. Del Toro added that series would have a relatively short total length as it will strictly follow the manga’s 18 volumes with nothing added to increase seasons or episode count.
Monster is currently available in manga form by Viz Media and in anime form by Siren Visual over in Australia. There are currently no plans to have the series licensed in the United Kingdom nor the United States.