The two are not related, Emiya Shirou, the male protagonist in the Japanese love adventure game "Fate/staynight" and its derivative works, a second-year student of the high school of Suizunhara Academy, ten years ago The only survivor of the fire caused by the Fourth Holy Grail War in Fuyuki City.

Because of the agreement with Emiya Kiritsugu, he aims to be a partner of justice. Due to his childhood experience, he is obsessed with saving lives and continues to suffer. Appeared as Saber's Master in the Fifth Holy Grail War.

Kotomine Shirou is a secondary created virtual male character in the Fate series, belonging to a subspecies of Emiya Shirou. Born on April 15th. The adopted son of Kotomine Kirei.

Extended information

Character background of Emiya Shirou

A trainee magician who inherited Kiritsugu’s will. He is a second-year student in Group C of the private Suogunhara Academy and is the protagonist of the story. He was involved in a fire ten years ago, but was rescued by Emiya Kiritsugu and became the only survivor. Later, he became Kiritsugu's adopted son and received basic training in magic. Kiritsugu passed away five years ago and is now living alone. However, Taiga Fujimura and Sakura Matou come to Emiya's house for dinner almost every day, so the house is very lively.

He accidentally summoned Saber (Artoria Pendragon) and participated in the Fifth Holy Grail War as the Master. Fight to stop this war. At first, he could only perform simple strengthening magic, but his talent for projection magic, which could be copied even with Noble Phantasms, eventually blossomed.

Character introduction of Kotomine Shirou

Kotomine Shirou, if Shirou’s adoptive father is a character in Kotomine Kirei’s IF story. Before Fate/Zero women exploded in popularity among fans, Kotomine Shirou was very popular among Fate/staynight fans.

The more famous secondary creations related to Kotomine Shirou are the "Kotomine Shirou's War Audit"/"ProtoMessiah" series (commonly known as ガリヘンガー) of the fan website "onthelock", SS search and submission website Arcadia's "Eight", fan music club WAVEamp; FAIRIAL's 2012 April Fool's Day project "Fate/Protoreplica" (the surname of Shirou who appeared in it was hidden, and the audience guessed that his surname should be Kotomine).

In the novel "Fate/Apocrypha" by Yuichiro Higashide, there is a character named Kotomine Shiro (pronounced the same as Kotomine Shirou), and his appearance is somewhat similar from the setting set. Although there was speculation among fate fans that it might be a parallel world line where Emiya Shirou was adopted by Kotomine Kirei, etc., it was later confirmed that it had nothing to do with Kotomine Shirou.

The father (adoptive father) was changed from Emiya Kiritsugu to Kotomine Kirei.

Without official confirmation, most of the secondary creations have based on Kotomine Kirei's character, setting Kotomine Shirou as a gentle man with a bad personality. Due to his adoptive father's relationship, his profession is a priest, and the weapons he uses are also black keys.

Baidu Encyclopedia - Emiya Shirou

Baidu Encyclopedia - Kotomine Shirou