"Drink it?"
Shirou Emiya stared at the Black Mud on the ground, lost in thought.
"There's no way I'm drinking that!"
Rin Tohsaka still couldn't fathom how Shirou Emiya, whose knowledge of magic was barely at an elementary school level, had managed to manifest a Reality Marble. "No matter what..."
Rin turned to see Shirou scooping up the Black Mud with a leaf, ready to drink it.
"Are you really going to do this? That's hell you're walking into!" Archer feigned concern, though his eyes gleamed with morbid curiosity.
"Even if it is, I have to keep moving forward!" Shirou stubbornly refused, opening his mouth.
"You're actually going to drink it?!" Rin swiftly knocked the Black Mud from Shirou's hand. Whenever saving the world was involved, this idiot's brain circuits short-circuited. She then kicked Archer hard.
"No one would think you were mute if you kept your mouth shut! Why don't you take a sip yourself?"
"Should I give it a try?" Archer stroked his chin, as if genuinely considering it. "But I've never heard of a Servant acting as a vessel for another Servant. At most, we can borrow each other's spiritual foundation. Besides, I have a feeling something bad would happen if a Servant touched that stuff."
"So, to sum it up—"
Rin Tohsaka couldn't take it anymore. She leaped forward and kicked Archer, who was still spouting nonsense, to the ground. "Once this is all over, I'll give you a proper magecraft lesson. Right now, the priority is to connect Shirou to the Holy Grail and make him a Lesser Grail!"
"Become a Lesser Grail?" Shirou Emiya asked. He already knew from Rin the consequences of such a fate—essentially handing his life over to someone else's whims. Yet he hesitated not at all.
"Tell me what to do."
"Shinji Matou must have had a key item implanted in him by Zouken Matou, one that allows him to become a Lesser Grail. These things are typically placed in the body's most vital part—most likely his heart."
Rin observed Shinji's grotesque transformation, his flesh still multiplying. "He's turning into this because his own magic circuits can't handle the functions of a Holy Grail. Plus, it's not a proper Grail to begin with."
She continued, "If a normal magus were to become this incomplete Lesser Grail, they'd be corrupted by All the World's Evils and become a vessel for Angra Mainyu. First, we need to extract Shinji from there."
"But this Black Mud... our servants can't touch it directly. There's no foothold for us to reach him."
Archer's mobility was flawless, but if he touched All the World's Evils, his spiritual foundation might be corrupted, and he couldn't predict what would happen then.
"We have to rely on you, Rin," he said.
Rin Tohsaka stared at the black mud flowing across the ground, wishing she could avoid stepping into it. But as the de facto administrator of Fuyuki's leyline, she had no choice. "Fine, fine. I'll drag that troublesome guy out myself."
"Let me handle it," Shirou Emiya offered. "Even if something unexpected happens, I can directly receive Shinji Matou's heart."
Shirou had long prepared himself to become a sacrifice, but he still couldn't reconcile saving others at the cost of someone else's life. "But if Shinji loses his heart... what will happen to him?"
"What will happen?" Archer scoffed, his disdain for his past naive self evident. "That's the nature of a Hero of Justice—sacrificing others to achieve salvation. Sacrificing this guy for the sake of the future? It's a worthwhile trade. Besides, he brought this on himself through his own resentment. Cause and effect—it's all his doing."
"But..."
"No buts! Are you just going to let him keep spewing this black mud?"
Archer couldn't stand Shirou Emiya's indecisive demeanor any longer. He knew exactly how to strike at Shirou's greatest weakness.
"Are you so worried about this guy's safety that you'd let the Fuyuki incident from ten years ago repeat itself?"
"I won't become you!" Shirou retorted.
"Oh? And what will you do about it?" Archer challenged.
Just as Rin Tohsaka was starting to get a headache from the tense standoff, a soft hand landed on her shoulder. She turned to see a familiar young girl. "Sakura?"
"Senpai, you don't need to trouble yourself with this. Leave it to us."
Sakura Matou had brought Medusa and Medea with her.
"Medusa, I'm counting on you."
Thanks to her aerial mobility, Medusa could easily evade the Black Mud and retrieve Shinji Matou. She simply needed to avoid the grotesque limbs sprouting from the corruption, a simple task for someone with her high Riding skill.
"As for the heart problem, Miss Medea can handle that."
Although Medea's Noble Phantasm was the opposite of her Lily-era Pain Breaker, her healing magic had become even more refined than before. She could guarantee Jason's survival for a while, but there was no assurance of long-term recovery.
"Shirou-senpai," she said, "please don't hesitate to remove my brother's heart. It's an emergency, so you can be rough. He definitely won't mind."
Sakura Matou's smile was gentle and demure, but Shirou Emiya couldn't shake the feeling that there was more to it. Still, basic gratitude was necessary.
"Sakura, thank you so much!"
"A heart transplant?" Medea replied. "That kind of thing should be left to Asclepius. He'd probably be interested."
Medea felt utterly exhausted. She had rushed straight here after stabilizing the barrier.
"Unfortunately," she said, "Mr. Jason is still in critical condition."
Sakura had seen Jiang You's notebook, which contained a charred human figure. Asking him to use his Noble Phantasm in his current state would be too much to ask.
"We'll have to rely on you, Miss Medea," Sakura said.
Only then did Medea realize she was responsible for this mess, and she awkwardly averted her gaze. After this was over, she resolved to temporarily leave Jason alone and get some much-needed rest.
A silver meteor streaked past the tower's apex. With deadly precision, Medusa ensnared Shinji Matou, the Flesh Mountain's core, with her weapon and yanked him free. The speed was so violent that several of Shinji's bones snapped. Fortunately, he was in a deep coma, his life force rapidly draining away; otherwise, he would have been sobbing uncontrollably.
Because of Sakura, Medusa showed Shinji no mercy, tossing him onto the ground like garbage.
Deprived of its core, the Flesh Mountain went berserk. It forcibly grew a massive hand, desperate to seize a new source of sustenance.