Watanabe is Kei Nagai's classmate.

High school student Kei Nagai is struck dead in a grisly traffic accident, but immediately revives to learn that he may not be like every other human. Instead, he may be a mysterious almost immortal being granted not only the powers of rejuvination but the abilities to see super-natural beings. Scared, he runs away, and is aided in his escape from society by his friend. Unfortunately for Kei, the manhunt is on and he will soon be caught within a conflict between mankind and others like him as they prepare to fight a new war based on terror.
 
(Source: Kodansha USA)
 
Notes: 
Includes 13 extra chapters. 
- Nominated for the 7th annual Manga Taishou Award. 
- Nominated for the Readers Award in the 18th Tezuka Osamu Cultural Prize. 
- Nominated for the 38th Annual Kodansha Manga Awards in the Seinen category. 
- Nominated for the 40th Kodansha Manga Awards in 2016 in the General category.

Kei Nagai’s body should have died when a truck slams into his body, but instead, he finds himself resurrected with all of his wounds healed. Now revealed to be an Ajin, one of a mysterious new breed of immortal demi-human, he’s been marked with an international bounty, and in the eyes of the world, Kei is a specimen to be taken by any means possible. Now he’s on the run, and his only hope is to discover the terrifying secrets behind his new abilities before he’s forced to use them in battle! 
 
(Source: Sentai Filmworks)

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__Birth Place:__ Potsdam, Brandenburg, Germany

He is also known as the german voice for Tom Holland aka Spiderman (Marvel Cinematic Universe), Thomas Brodie-Sangster aka Newt (Mazerunner) or Dylan Minnette aka Clay (13 Reasons Why).