Sakura held her breath and pressed herself still behind the altar. She couldn't hear footsteps any more; either Maroi hadn't moved from where she'd last heard him speak, or far more likely, he was sneaking around behind her, using chakra to muffle his footsteps as he prepared to sneak attack her.
She urgently needed to find a way out of this secret room; with her own chakra sealed away by the Celestial Prison Jutsu, she hardly relished the prospect of facing a man who could hurl lightning from his fingertips, armed with nothing but her bare fists.
As she searched for something to throw and draw Maroi's attention away from her, Sakura's gaze fell on Mui's charred form lying on the ground before her. His chest rose and fell irregularly; he was unconscious and badly shocked, but still alive.
Seals and sealed chakra alike could persist after death, yet the Celestial Prison Jutsu was perhaps one of the few exceptions to this rule. One of its binding laws forbade the branded from straying too far from the caster, which meant individual seals were constantly gauging the space between themselves and Mui.
This dependence on a living heartbeat lent credence to the other prisoners' whispers that killing Mui would shatter their bonds; just like one bad like of code, one failed check might send the rest of the Celestial Prison Jutsu's formulae into a cascade of catastrophic failures.
If she could only reach him, she might at last be free of this accursed seal… but killing was one thing; executing an unconscious, unresisting man was quite another— even if said man had only moments ago tried to sacrifice her to an evil box.
A few more tense moments passed, with nothing happening.
Sakura peeked out from behind her hiding place. Maroi was nowhere in sight. She stole a glance over her shoulder and shivered at the sight of the Box of Paradise embedded in the wall, its matt black surface carved in the eerie likeness of a demonic Asura.
Maroi's goal stood right behind Sakura, glaring silently at her back. Why wasn't he attacking, she wondered? He had her dead to rights; his Celestial Prison Seal clearly wasn't stopping him from using his powers, while she was sealed up even tighter than before. He only needed to kill her and claim his prize.
"Shit, shit, shit!" Sakura swore. "I can't waste any more time here!"
Unfortunately, she didn't have the luxury to stand about and ponder why Maroi was playing hide-and-go-seek with her; the woman in the monkey mask and Kazan still had to be stopped before they dragged the world into the Fourth Shinobi World War ahead of schedule.
Sakura stood, lifted her foot above Mui's head as if to crush it like a watermelon… then removed it, gave a slight shake of her head, and sprinted into the dark tunnel that appeared to be the room's only exit.
…
Moments later, as Sakura's footsteps faded into the distance while she ascended the stairs out of the prison's subbasement, Maroi's form shimmered into view in a corner of the room. He mopped his clammy forehead with his sleeve and let out a shaky sigh of relief.
"Phew, she took the bluff… I thought she'd never leave…" he gasped. "That was close, too close, I was sure old Mui was done for… Honestly, this kind of stress can't be good for my heart. Man, Konoha's newest generation is full of monsters… but everything's going to be fine once backup gets here, even the Legendary Sannin can't deal with that many elites at once..."
Other than to incapacitate him for capture, the reason Maroi had attacked Mui with a thunderclap arrow was to knock him down before Sakura could obliterate him. Though the blue markings on her face did not resemble those shown in the bingo book depictions of Jiraiya the Gallant, he had immediately recognised her for what she was: an Honoured Sage, a monster who surpassed the level of a Kage. Fearing that any wrong move might lead to a critical mission failure, and his own death, Maroi concealed himself and waited for Sakura to leave.
If only he'd known that Sakura had already expended all her senjutsu chakra, and that he'd missed his one and only chance to eliminate someone who had already humiliated the Hidden Cloud and would become an even greater nightmare for them in the future…
"Oh well, I'm not one to look a gift horse in the mouth," Maroi muttered, lowering himself into a squat next to Mui's smoking body. "Right then, time for a bit of emergency first aid on Mr Gatekeeper. Can't have you dying on us now, can we, old Mui?"
Mui groaned upon hearing his name.
"Oh, don't be like that," Maroi chuckled. "Sure, it's a little chilly at this time of year, but I think you'll find your new home in Kumogakure quite accommodating…"
…
The Box of Paradise was an Ōtsutsuki weapon forged for wars of conquest against lesser lifeforms. Autonomous puppets, capable though they were, lacked the wit for certain tasks, so the Ōtsutsuki had designed an autonomous weapon that could create slaves, who would serve them while they rested between campaigns. Scouring the cosmos for suitable worlds to drain was tiresome work, after all.
In any case, after Shibai's apotheosis, the knowledge required to operate the Box somehow fell into human hands. In Kusagakure, the keeper of that knowledge came to be known as the Gatekeeper— master of secret lore, entrusted through generations with the incantations and seals that opened and commanded the Box.
As Gatekeeper, both Mui and the knowledge locked within his mind were vital to Kumo's plans— and if Sakura hadn't let her conscience get the better of her, she might have spared herself a great deal of trouble.
Indeed, the Box of Paradise was not supposed to be an uncontrollable weapon of mass destruction, unlike the demon Mōryō. In the original timeline, the only reason the Box had gone berserk was because its Gatekeeper had died before giving it an actual command it could recognise.
"Heed my wish," were Mui's last words. "Let me see my son Muku!"
As commanded, the Box had spat out Muku, now its puppet… and overcome by emotion at the sight of the son he'd lost— drawn into the Box years earlier during an experiment to awaken it— Mui failed to speak the final words that would have bound it to his will.
It ought to have been an emotional reunion between father and son.
However, after being sucked into the Box of Paradise, Mui's son had become a shell of his former self, consumed by the rage and resentment he'd felt when his father had unwittingly fed him to it. Muku had become Satori, the monster inside the box.
Taking leave of his senses and throwing all caution to the wind, Mui approached the hollow Muku, and with the faintest remnants of its former self crying out for revenge against the one who had abandoned it, the puppet struck down the puppetmaster who had let go of its strings. Deprived of a master and orders it could obey, the Box had turned to its own nature as a weapon for guidance and raged out of control… but in this timeline, Kumogakure was not about to let such a thing happen to their new, precious weapon.