Erasing the darkness in one's heart isn't something that happens overnight. It could take months at best, years at worst.
Killer Bee figured if Naruto stayed unconscious for a long time, Kazama and the others would start panicking.
When that happened, they'd come begging for his help, and he could use the chance to regain some pride after Kazama's earlier beatdown.
"Bee, you're one sneaky dude!"
The Eight-Tails, well aware of Bee's little scheme, teased him with a laugh.
"Haha, you know it! I'm the mighty Eight-Tails Jinchūriki, after all. Kazama made me lose face earlier, so I'm gonna get it back. I'm the only one who's faced the Waterfall of Truth, and I'm the only one who can help Naruto conquer the darkness in his heart. Just wait for the show!"
While Killer Bee was smirking to himself, Naruto, at the Waterfall of Truth, was drenched in sweat and trembling all over.
Kazama could tell something was wrong—this was clearly a sign of Naruto losing control, like he was about to go haywire.
If this went on too long, Naruto might die before he could even learn to control the Tailed Beast.
"Bee, what's happening to Naruto?"
Yamato, also noticing Naruto's condition, demanded answers.
"He's battling the darkness in his heart. If he wins, he'll wake up just fine."
"And if he loses?"
"Well, then…"
Killer Bee let out a dramatic sigh, playing it up.
"Damn it, why didn't you say that sooner?!"
Yamato moved to wake Naruto, but Killer Bee quickly blocked him.
"I wouldn't do that if I were you. You'll only make things worse and speed up his failure."
"Then what do we do?"
Seeing Yamato take the bait, Killer Bee grinned smugly.
"To help Naruto now, only another Jinchūriki like me can enter his mental world and fight his inner demons alongside him."
"Then get moving!"
At Yamato's urging, Killer Bee shook his head theatrically.
"Entering a mental world takes a ton of chakra. How about this: let me rest for a day, then I'll help Naruto."
"No way! What if something happens to Naruto in the meantime? We can't take that risk. Please, for the sake of the alliance between Konoha and Kumogakure, save Naruto now!"
"Yeah, we're begging you!"
Hearing Yamato and Guy's pleas, Killer Bee shot a smug glance at Kazama, clearly waiting for him to beg too.
"Helping Naruto beat his inner demons? I can do that."
Kazama stepped forward, preparing to use his Seiren Chishinbi.
The Seiren Chishinbi could calm the mind and dispel the symptoms of losing control, perfect for a situation like this.
"What? You?"
Killer Bee burst out laughing at Kazama's words.
"Kazama, little bro, I know you're strong, but beating inner demons isn't just about raw power. You've gotta be a Jinchūriki to enter another Jinchūriki's mental world. You can't even get into Naruto's head, so how're you gonna help?"
As Killer Bee rambled on, he suddenly noticed a wisp of emerald-green flame flickering in Kazama's hand.
The flame then flowed into Naruto's body.
"What, you planning to burn Naruto to death with some Katon jutsu? Haha!"
Unaware of the Seiren Chishinbi's unique properties, Killer Bee mocked Kazama again with a laugh.