Yes, this is indeed legit.
It was announced on Friday in the 20th anniversary event of One Piece that the One Piece manga is getting its own live-action Hollywood television show. This has been made possible due to the partnership of ITV Studios and producer Marty Adelstein. Adelstein was also involved in the production of Teen Wolf and Prison Break. The live-action series will be produced by Tomorrow Studios, the same production company who is working on a live-action series adaptation of Cowboy Bepop.
For the benefit of people who haven’t followed the series yet, One Piece is a manga series about a starting pirate named Monkey D. Luffy who wants to claim the legendary treasure called “One Piece”. A lot of pirates like him want to get this rare treasure so he formed a crew and together went on different quests and adventures. Along the way, he meets new friends and meet some baddies along the way.
The manga series began in 1997 in the Weekly Shonen Jump and still considered as one of the most popular and mostly read manga series in Japan. The series has sold more than 350 million copies in Japan alone since April and over 66 million copies internationally. The One Piece manga was able to achieve a total of 320,866,000 copies printed worldwide (as of December 2014) in which it received a world record in June 2015.
Aside from the record-breaking manga series, its popularity also paved way for an anime adaptation which premiered in 1999 as well video games, anime films, toys, theme park attractions, and more.
More info regarding the upcoming live-action adaptation will be released the soonest time.
Source: Matan Web