Arc 2The Sea Monster Awakens
Shirou built an alliance with Hundred-Faced Hassan while investigating the other Masters, then intervened when Caster’s sacrificial ritual endangered children and Irisviel. Caster’s Grimoire unleashed a giant Sea Monster, and Shirou, Saber, and Lancer prepared to fight it before Lancer turned on Irisviel.
- Shirou used a modified Command Spell to transform into his adult body at the cost of his life, then killed Ryunosuke Uryu and revived him as a Living dead for an experiment.
- Shirou persuaded Hundred-Faced Hassan and Loli Hassan to cooperate with him, and learned that Kirei and Tokiomi were allied and Gilgamesh was their powerful Archer.
- Shirou encountered Irisviel in Shinto, later watched Saber fight Lancer, and investigated Kaineth’s workshop, where he found three dormant Mana Cores resembling Melusine’s aura.
- Shirou helped Hundred-Faced Hassan steal the Mana Cores, then learned Caster was draining people to restore Ryunosuke and had mistaken Saber for Jeanne d’Arc.
- Shirou rescued children from Caster’s ritual in the Einzbern forest and joined Saber in destroying Caster’s monsters, taking the Tome of the R'lyeh after Caster died.
- The Tome absorbed the scattered monsters and grew into a Sea Monster, while dead Ryunosuke used his Command Spells to avenge Caster and finally died.
- Shirou and Saber agreed to lure the Sea Monster away from Miyama Town so Saber could destroy it, and Lancer joined them before attacking Irisviel.
- Shirou wounded Lancer as he intercepted the attack, and Lancer admitted he had targeted Irisviel to eliminate her as a Master.