Nguyen is an assassin employed by Murder, Inc. and a former colleague of Shunsuke Saruwatari. His knowledge of the killer industry in Fukuoka prompts Saruwatari to quit his job and move, and Nguyen later follows on assignment to kill Kazuki Saitoh.
He is described as having strong features that make him stand out as a foreigner. He sports a goatee and wears his brown hair pulled into a high ponytail, and in the manga, he has lines shaved into his undercut. Despite his foreign appearance, he has no trace of an accent.
Nguyen is a skilled professional killer. He pays attention to his surroundings, including people and rumors, and keeps himself well-informed. Despite being an assassin, he has an amiable side, showing admiration and friendliness toward his close colleagues.
Nguyen entered Murder, Inc. around the same time as Saruwatari. After Saitoh failed an assassination assignment, Nguyen was tasked with making the kill for him.
Niwaka Samurai Impersonator ArcEdit
Nguyen joins Saruwatari for dinner, where he discusses Saitoh's move to Fukuoka and the abundance of killers in the city. Saruwatari is intrigued by the idea of a killer of killers and immediately decides to quit the company.
Nguyen contacts Saruwatari from Fukuoka to inform him of his assignment and invite him for drinks. He reluctantly agrees to sending a Saruwatari a list of mediators in Fukuoka prefecture, a move that could cost him his life as well as his job if discovered by his superiors.
Enokida meets Nguyen at a ramen shop in Nakasu. Nguyen is fronting as a scout, and he asks for Enokida's help in finding Saitoh. Enokida gives him Saitoh's home address before calling Saitoh to warn him. Saitoh receives the message in time to notice the killer on his balcony, and Nguyen chases him onto a train at Hakata Station bound for Kokura. Xianming Lin arrives to help Saitoh put distance between him and his pursuer. Lin lands a punch on Nguyen's face when he enters the car and disarms him, but Nguyen throws a fake grenade to bring Saitoh into the open and seize a chance to pick up his gun. A bullet grazes Lin's leg, but when the train takes a sharp turn that Lin is expecting, he disarms Nguyen again and lands three gunshots to his chest.
Having worn a bulletproof vest, Nguyen survives the gunshots but takes the full force of the blows. He is contacted by Enokida, who has captured Saitoh. After Yamamoto's cosmetic surgery, Nguyen believes him to be Saitoh, and promises to return the pain he sustained from Lin before killing him.
Shou Wang ArcEdit
While he has since returned to Tokyo and does not make an appearance in the third light novel, Nguyen is an acquaintance of Yang's and informs him of seeing a killer matching Lin's description in Fukuoka two weeks prior to Yang and Feilang's arrival in Japan.
- In the anime subtitles, his name is spelled "Gwen." The names "Gwen" and "Nguyen" have the same spelling and pronunciation in Japanese.