"This is what we need to unseal Satoru Gojo-the Back of the Prison Realm."
Tengen held the black cube, their voice as steady as a stone worn smooth by a thousand years of flowing water.
"Huh? The back?" Itadori tilted his head.
"I've never heard it called that before." Fushiguro's gaze settled on the black cube, his brow creasing slightly. "So you mean it's the rear gate?"
"That's right." Tengen nodded, the movement looking somewhat sluggish on a face that no longer resembled a human's.
"Before Kenjaku found the Prison Realm, it was always outside my barriers. I suspect it was overseas. I originally tried to seal this rear gate to suppress the presence of its front, but unfortunately, it didn't work." Tengen paused, those hollow eyes lowering slightly. "Likewise, another part of Satoru Gojo is sealed inside this rear gate."
"Then... we just need to open this?" Megumi Fushiguro tilted his head.
"No." Tengen shook their head.
"The authority to open the Prison Realm still rests with the owner of the 'front.' To pry this open, we need the Inverted Spear of Heaven, which forcibly nullifies all Cursed Techniques, or the Black Rope, which disrupts their effects." Tengen raised their eyes, their gaze sweeping over Fushiguro's face, then Itadori's. "We must have one of the two."
"But Satoru Gojo destroyed the Inverted Spear of Heaven twelve years ago," Tengen added, their tone as flat as if they were reading a report.
"What on earth was Mr. Gojo doing?!" Itadori's voice rose half a pitch, filled with the exasperation of someone asking why he had dug his own grave.
"Kashimo also acquired all the Black Rope at the end of last year." Tengen's voice dropped again, like a stone tossed into water.
"What the hell?!" Megumi Fushiguro gritted his teeth,