Parasyte -the maxim-
寄生獣 セイの格率 (original)
A species of parasitic aliens descends on Earth and quickly infiltrates humanity by entering the brains of vulnerable targets; insatiable beings that gain total control of their host and are capable of transforming themselves to feed on unsuspecting prey. High school student Shinichi Izumi falls victim to one of these parasites, but the creature fails to take over his brain and ends up in his right hand.
Starring Nobunaga Shimazaki, Aya Hirano, Kana Hanazawa, Miyuki Sawashiro, Atsuko Tanaka, Akira Ishida, Ayumu Murase, Kazuhiko Inoue, Daisuke Namikawa, Hiroyuki Yoshino
It's a animation and drama show, and has a rating of 8.3 out of 10 from Imdb which is very high for this kind of show.
Watch it here
Not found streaming from United Kingdom.