Grigori Rasputin was a historical figure in Russian history. He volunteered to help heal Tsarevich Alexei who was suffering from hemophilia. Before his exploits were known, he was believed to have mystical powers, and an apparent closeness to his religion, Christianity. His aid to the Tsarevich helped cement his relationship with the ruling noble family Romanov. His image as a monk, spiritual healer, prophet and man of God was quickly spread throughout Russia. The Tsar and his family depended on him heavily for advice.
This adds to the apparent dislike of him and the Romanov family by others; nobles, politicians, journalists and even the Russian Orthodox Church. He became a controversial figure, and accused of abusing his privileges with the noble family for control over the rulings in Russia, such as suggesting the ill-equipped Tsar to be in full command over the Russian military. Truthfully, Rasputin succumbed to all worldly temptation; such as sex and alcohol, believing that it can also be a path to piety and salvation.
This controversy culminated into hatred, and subsequently many attempts on his life were made. He was (reportedly) stabbed, poisoned, shot, beaten, castrated and finally drowned in the Moika River. This is almost guaranteed to be false; a lie to prevent him from being canonized (made into a saint after death) due to a rule which prevents drowning victims from being made saints, while simultaneously making him seem demonic or a warlock (devil pact maker, male witch).
His life, as well as his death, became the stuff of legends; it was said that he survived all the murder attempts, and even after his body was buried, dug up and burned, it seemingly went alive, if only for a moment.
Rasputin appears as a secondary antagonist for most of the game. Even though Raidou Kuzunoha vs. The Soulless Army is set after Rasputin's death, he appears in Tokyo as a Dark Summoner, using his powers for profit rather than for the good of the people.
He crosses paths with Raidou Kuzunoha the XIV while Raidou is investigating the disappearance of Kaya Daidouji. Rasputin was apparently hired by General Munakata in order to insure that his Super Soldier Project went as they should, but he is actually an artificial human sent back in time from Tokyo Millennium to deal with the unknown events that are changing the past.
However, Rasputin's true purpose seems to fall down the ladder of priorities as he begins to behave like a lush, drinking and hitting on women. It is revealed he is also a time traveler from the future, apparently sent to maintain the timeline, but ignored his mission to pursue his own goals. By the end of the game, it is implied Rasputin remains in Raidou's time to become more "human."
He ambushes Raidou as he attempts to talk to Kiyoshi Daidouji in his textiles factory, summoning Chernobog against him. Later on, he's confronted at the Catholic Church, where he admits he killed and impersonated Elfman to gain his money and the respect he commanded. Following this, he directly confronts Raidou, using his trademark Matryoshka dolls as weaponry. He is then defeated, revealing his inhuman anatomy and status. However, he was not destroyed permanently.
After this, Rasputin returned as Raidou killed Mishaguji in the Radio Tower, banishing him to another timeline. When Raidou returned from the exile, Rasputin was waiting for him at the Narumi Detective Agency, stating his "contract" was over, handing over items necessary to access the Subterranean Shipbuilding Facility.
Later on, having fully abandoned his original purpose, Raidou knocked him unconscious at the Shin-Sekai Soda Joint and took him to Dr. Victor both for analysis and for help dealing with issues regarding the rocket intended to destroy Tai-Itsu, the satellite providing the Soulless God Oumagatsu with power. After Rasputin had done so, Dr. Victor reassembled him and let him go after "borrowing" some parts and "slightly" damaging him.
Rasputin returns in the sequel and has a minor role in the game. He provides information to Raidou, as well as continuing to pursue Tae's affections. Certain optional quests are also provided by Rasputin, with the client listed as a "Dark Summoner." His knowledge as a Dark Summoner comes in handy during Raidou's investigation when Raidou must locate a special material to forge a sword capable of defeating the indomitable Apollyons.
During the scene in Tsukigata Village, Rasputin will replace Tae if the Raidou is Neutral-aligned when the villagers take someone Raidou knows as a hostage. When Raidou had to find a way to defeat Apollyon and ask Rasputin for the way in Ginza-Cho, he will give Raidou Element #115 if Raidou chose to save him during the scene in Tsukigata.