The next day, Nanatsuki arrived at the Technology Development Bureau's lab.
"Kisuke, why are you sleeping here?"
He found Urahara Kisuke lying on one of the long benches in the lab.
"Ah... Captain? It's already morning...?" Urahara yawned and sat up from the bench.
"I've been trying to contact you through the Denreishinki all morning. Don't tell me you forgot—Shin'o Academy invited us to attend the Live Blade Tournament today."
Nanatsuki shook his head in mild exasperation.
Kisuke had clearly gotten too absorbed in his research again and lost track of time.
"Ah… is that today? I think I dropped my Denreishinki somewhere..." Urahara looked around and eventually spotted the device under a far table.
"The spiritual signal from the Denreishinki is only detectable when it's close to your body... I should probably make a home-use version. Increase the signal strength... maybe even add a vibration alert..." Urahara muttered to himself.
In the blink of an eye, he had already piled another list of development tasks on his plate.
"Let's leave that aside for now... Captain, I've made some new progress recently." Kisuke pocketed the Denreishinki, rifled through a stack of papers, and pulled out a small cube that looked like a die.
"What's inside this... is it Hell Reishi?"
Nanatsuki picked up the cube and instantly sensed the presence of hellish energy within.
It was a six-sided die, each face engraved with Kidō-style formula runes.
The current research into Hell Reishi had ended up falling under Kisuke's domain.
Mayuri Kurotsuchi had initially competed with him over it, but once Reishi Shell technology was declassified, Mayuri's attention shifted fully in that direction.
To him, Reishi Shells were closer to the power of a creator—and far more worthy of study than Hell Reishi.
"I managed to use Hell Reishi to create a spiritual tool," Kisuke pointed to the engraved runes on the cube. "Take a look—these are all Kidō-type inscriptions, but the results were surprising. The performance is nearly identical to when using normal formula arrays!"
Kisuke had been exploring ways for Shinigami to utilize Hell Reishi directly.
"Really? Then can you demonstrate how it works?"
"It's easy. Just press one of the faces and toss it."
Following Kisuke's instructions, Nanatsuki pressed one of the die's faces and threw it onto the ground.
The die rolled once, then settled with the pressed face pointing upward. The engraved Kidō formula activated instantly.
A crimson binding rope of light shot out from the cube.
"That's Bakudō #4: Hainawa, right? But the color's different. Does Hell Reishi alter the color of Kidō?"
Nanatsuki recalled that Hainawa's rope of light was usually not red.
"Hell Reishi changes Kidō to red or black," Kisuke explained, bending down to pick up the die again. "It has strong assimilation properties. These tools activated by Hell Reishi—I've decided to call them Hell Spiritual Tools. Captain, got any better name ideas?"
"'Hell Spiritual Tools' sounds just fine," Nanatsuki nodded. "If Shinigami ever need to explore Hell, these tools could be a huge help."
Though Shinigami could absorb Hell Reishi in emergencies to replenish Reiatsu while in Hell, doing so placed extreme strain on the spiritual body.
Overexposure to Hell Reishi might even transform a Shinigami into a Hell-based lifeform, permanently bound to Hell like those who had already fallen into it.
With Kisuke's Hell Spiritual Tools, Shinigami could cast Kidō without using their own Reiatsu.
"Consider this die a memento, Captain!" Kisuke offered it to him. "It's the very first Hell Spiritual Tool ever manufactured by the Technology Development Bureau!"
"Then I'll place it in the lab... six faces for six Kidō spells. It's already very practical." Nanatsuki rotated the cube in his hand. "But the activation method feels strangely familiar... doesn't it resemble the Quincy's spiritual tools?"
Most Shinigami tools required one's own Reiatsu to activate. Semi-automatic triggers like this were rare.
By contrast, Quincy tools were generally powered by external Reishi.
"Sharp as ever, Captain!" Kisuke raised a brow in surprise. "You're right—the die's triggering mechanism was inspired by Quincy tech."
With a weary expression, Kisuke added, "Trying to integrate all those functions cost me a lot of hair."
"Thanks for the hard work!" Nanatsuki patted him on the shoulder and smiled. "But take a break—let's head to the Shin'o Academy and watch the Live Blade Tournament today."
"It really has been a while since I rested…" Kisuke stretched lazily. "Guess I'll unwind for once!"
Nanatsuki and Kisuke made their way to the Shin'o Spiritual Arts Academy.
Nanatsuki hadn't been there in quite some time.
He and Kisuke were invited as guests to observe this year's Live Blade Tournament.
Both Chijō Sōya and Tōsen Kaname had entered the tournament—and made it to the finals.
Today was the day of their final match.
At the gate, they ran into Shirai Riko, who was guiding guests.
"Captain Katori! Vice-Captain Urahara!"
"Riko-sensei, it's been a while."
"It has! The seating arrangements have changed this year—please follow me..."
"The viewing platform's been raised, huh?"
Nanatsuki glanced toward the audience seating. The elevation had noticeably increased, giving a clear view of the arena.
"Your students' performance in the last tournament was a bit... overwhelming. For everyone's safety, we made special adjustments."
Shirai Riko smiled. "Thanks to your efforts, the Live Blade Tournament has become one of the most anticipated events in the Seireitei. Our budget increased because of it—otherwise, we wouldn't have been able to afford so many Sakkise stones!"
The viewing platforms had been raised, and the outer walls were now reinforced with Sakkise, a material that could block spiritual energy.
With both Sakkise walls and Reishi barriers in place, audience safety had greatly improved.
Led by Shirai Riko, Nanatsuki quickly reached the VIP seating.
"Teacher—over here!" Yoruichi waved, patting the empty seat beside her.
"Sorry, am I late?"
Nanatsuki sat down next to her.
The guest seats were already packed.
Besides him and Urahara Kisuke, everyone else had already arrived.
"Late? You're lucky you didn't miss the whole match," Kyōraku Shunsui rolled his eyes.
"I stopped by the dojo yesterday to coach Sōya and Kaname, then dropped by the Twelfth Division this morning. If I hadn't gone, Kisuke would've forgotten all about the tournament."
"I got too into my research last night and forgot there was anything else going on today..." Kisuke scratched his cheek sheepishly. "Thank goodness Captain woke me up!"