Ep 5. The Two Magi (Part 1)

Shirou is still recovering from his injuries from his previous fight, but Saber is eager to continue their training. Meanwhile, Rin is still trying to figure out the identity of the mysterious Archer. During a meeting with other magi, Rin learns that there is another magus in the city who is also collecting mana. Rin suspects that this magus may be a threat to the Grail War and decides to investigate. She enlists Shirou's help, much to Saber's chagrin.

The two of them head out to investigate and stumble upon a magical barrier. Rin recognizes the spell as belonging to the Tohsaka family, which means that the other magus must be one of her relatives. After some sneaking around, they find themselves face to face with Kirei Kotomine, the priest from the Church. Kirei seems to be interested in Rin's progress in the Grail War, but Rin is suspicious of his motives.

After leaving Kirei's presence, Shirou and Rin follow a trail of mana and end up in a graveyard. There they find another magus, a young girl named Illyasviel von Einzbern, who claims to be a master in the Grail War. Rin is shocked to see Illya, as her family had supposedly stopped participating in the Grail War after their disastrous attempt to summon the Grail in the past. Illya invites Shirou and Rin to her mansion to discuss the war.

At Illya's mansion, Shirou and Rin meet Illya's Servant, a powerful Berserker who seems to be controlled by a homunculus. Rin is impressed by the power of the homunculus, but also disturbed by its unnatural existence. Illya's true motive for inviting Rin and Shirou soon becomes clear: she wants to form an alliance with them against the other magi in the war. She claims that she is the best positioned to win the war, and that she will share the Grail with them if they help her.

Shirou is skeptical of Illya's offer, but Rin agrees to consider it. The episode ends with Shirou and Rin leaving Illya's mansion and discussing their options. Rin is torn between her desire to win the Grail War and her concerns about the potential dangers of forming an alliance with Illya. Meanwhile, Shirou is still struggling with his own motivations for participating in the war. He knows that he wants to save people, but he's not sure if he can handle the violence and destruction that comes along with being a master.

Overall, this episode sets up the next stage of the Grail War by introducing a new player and raising the stakes. The episode also delves into Rin's backstory and her connection to the other magi in the war. Fans of the series will enjoy the complex character development and the tense atmosphere.