AppearanceEditHe is 80 years old during in Fourth Holy Grail War, despite his advanced age, his physique is still very muscular like Mas Oyama. Risei's face resembles like an older Steven Seagal. Risei has the same eyebrows and mussed mullet as his son, joked as being the Kotomine clan Sorcery Trait. He gives of the appearance of an old soldier better suited to wearing a samurai costume in the Warring States era than a priest's cassock. Even with his cleft chin that makes him look like a character from Ninja Scroll, he "feels like a genuine Japanese person."
PersonalityEditHe is a close associate with Tokiomi Tohsaka, Risei actively supports him and conspires to ensure that Tokiomi will obtain the Holy Grail in the war, despite the fact that as a member of the Church, he should be ensuring only someone who is worthy of the a powerful artifact like the Grail should be obtaining it.
While he is proud of his son, who has demonstrated himself to be a perfect heir, Risei fails to understand Kirei in any sense. He believes that his son, who has recently lost his wife of two years, may be able to find some purpose in life again by aiding Tokiomi during the Holy Grail War.
Risei sympathizes Shirou Kotomine as he had devoted his entire life to the Lord, only to found tragedy in his end and to find something new for himself, Risei would be willing to sacrifice everything. Risei was never one to mourn over loss of wealth and willingly to provide Shirou with social status and funding. However Shirou lied to Risei about giving up on pursuing the Greater Grail and ironically he also did not understand his foster son true nature.
As a monk, he tried to reach enlightenment through asceticism and hardships. He treated his task of recovering holy relics from around the world as a pilgrim's ordeal.
When the Church first interfered with the ritual in Fuyuki during the Third Holy Grail War in the 1930s, held on the eve of World War II. They sent Risei who was not far from his twenties and he was in charged with the role of supervisor. While there, he became friends with the then-current head of the Tohsaka family and has maintained deep ties with the Tohsaka ever since.
His son Kirei Kotomine was born on the 28th December 1967 and thanks to his pious worship, Kirei was gifted with Magic Circuits from the divine sacrament. Because of Risei, Kirei had been working diligently as an Executor-in-training since an early age. He is responsible for teaching bajiquan to Kirei, his skill far outstrips his son.
His original design concept was "an older Steven Seagal".
Both Risei and Tokiomi, upon discovering that Kirei's command mantra had appeared three years before the start of the war, both came to believe that Kirei was destined to provide Tokiomi with an additional Servant and associated command spells for the upcoming war. Without informing Kirei as to the true nature of the mark that appeared, they transfer Kirei from the Church to the Mages Association as Tokiomi's pupil. Neither man reveals to Kirei that he can also obtain the Holy Grail, instead telling the young man that he is performing a mission for the Church.
He was involved with Tokiomi's plan to stage Assassin's death so that the other Masters perceive Kirei and Assassin had been defeated, and allowed the dozens of remaining Assassins to move freely without suspicion. He pretended to provide Kirei a place of refuge while Kirei provide support in the shadows.
As Risei conspires with Tokiomi, they eventually come to see that Caster and his Master prove to be too erratic and threaten Tokiomi's chances of winning the war. To this end, they arrange for Risei to offer additional command spells to the Master who manages to defeat Caster and his Master.After Caster's defeat, Kayneth Archibald El-Melloi approached Risei to obtain additional command spells. After Risei reluctantly gives what Lord El-Melloi has come for, the Master shoots Risei and leaves him to die in order to implicate Kiritsugu Emiya as the murderer. As he dies, Risei leaves behind a message containing a secret password that will provide his son with all the remaining command spells Risei could give out. Kirei arrives to find his father dead and his father's final parting gift, and comes to the conclusion that Risei died trying to protect him. Though Kirei sheds tears realizing his father cared about him till the end, he finds himself feeling the same feelings he felt when his wife died - the desire to have seen them die.
Risei has already passed away by the time the Great Holy Grail War has started. Fate/Apocrypha briefly mentions Risei's involvement in the Third Holy Grail War, however it differs to the timeline of Fate/stay night. After Darnic Prestone Yggdmillennia stole the Greater Grail, there were only two survivors on the field of battle. Risei stood next to the Einzbern's servant, the Ruler-class Amakusa Shirou Tokisada. Risei knew Shirou's true identity and he spoke to him in a way befitting his name. Risei questions Shirou's plan after the war and although he is clearly greater in both age and stature, he was quite nervous in front of Shirou. Shirou considers going on a journey when he remembers Risei mentioning about his journey in order to find enlightenment. Risei delighted from reply, he offered to help Shirou. Risei adopted Shirou and the boy gained a new identity. True to his words, he traveled the world as the foster child of Risei. With the help of Risei, Shirou obtained a place within the Assembly of the Eighth Sacrament.
According to Kirei in the Fate scenario, his father died trying to protect him.
Risei is a practitioner of bajiquan, but he does not utilize it actively in order to kill targets like his son engaging Dead Apostles. He is not an Executor, so he uses it as a form of self-discipline and meditation. He only trains with the goal of being able to fight rather than with the goal of being able to kill, so Kirei uses it in gruesome battles more often than him.
He, as the supervisor of the Holy Grail War, has a large number of Command Spells recollected from the previous Holy Grail Wars as the inheritance of the Masters who lost their Servants before the final battle. All Command Seals not used in time are entrusted to him and left to his judgement as the one presiding over the Fourth Holy Grail War.While their existence can already be called a kind of miracle possessing enormous power, they are still a form of exhaustible physical enchantment. This allows them to be transplanted or transferred through incantations. He is able to reserve Command Seals to anyone based upon his own judgement, allowing Masters renew more control over their Servants. The process only requires him to trace the faded marks of the used Command Seals and transfer his own to replace them. The process doesn't come with any pain like receiving them from the Grail, and it only takes a few minutes to complete.
The Command Spells managed by the supervisor are protected by holy prayers and may only be transferred through his permission, so it not possible to seize them through the use of thaumaturgy. Even after Risei's death, Kayneth Archibald El-Melloi is unable to take them. Only those who know the secret holy words, "God is spirit, and his worshipers must worship in spirit and in truth——" from John 4:24, are able to utilize them. Risei leaves the letters "jn424" transcribed in blood, so that it looks to be a secret message of unknown meaning to those not of the Christian faith. Kirei is able to identify it immediately, and upon speaking it, they are transferred one by one while accompanied by dull pain.