Reiryoku.

This is the energy that supplemented every living soul in Soul Society and a primary factor in the sustenance of life in general.

In loose terms, it is the ‘flow’ that is present as a soul pool in all sentient being, some more so that others, and it was the utilization of this ‘flow’ or the reaction it has with something that can channel it’s energy that brought about the effervescence that was called ‘Reiatsu’ – the ‘force’ of the ‘flow’.

The Reiryoku of every specie has an equal limit, regardless of how talented the individual is. Unfortunately, not everybody could reach the maximum potential of their race, so the racial limits held no concern for those aware of it as it was an already established fact that they would never reach it.

Between the two, Reiryoku and Reiatsu, the former was a dormant energy pool and the latter was an active fission of the former.

Reacting your Reiryoku with something, say a special soul blade, gave birth to the overwhelming explosiveness that was Reiatsu, and it was this that Shinigamis, or soul-based entities in the case of Itachi, used in their battles.

Upon saving the young ninja girl, Isshin had thought that Itachi would press him with an attack and that was what Itachi did as his blade passed unhesitatingly towards his left shoulder and when Isshin had brought his blade to block it, Itachi suddenly disappeared and three heads flew into the air as a reaction.

“Jigoku, Hibashira!” Isshin stabbed his sword into the ground and in a star-like pattern, torrents of flaming pillars rose into the air with two of them cutting off Itachi’s retreat for Isshin to pursue.

Itachi calmly asserted the position of the Shinigamis around them as he frantically tried to dodge Isshin’s angry outburst, a mostly unsuccessful attempt.

Isshin was physically stronger and fast enough to keep up and react with Itachi and his utilization of his Zanpakutō was something that was out of Itachi’s grasp.

“You’re good. But even you should know how futile this is.” Isshin stopped and pointed his flaming blade at Itachi.

This problem was that it was no longer Itachi having to deal with Isshin, but also the crowd of Shinigamis surrounding him.

The most surprising thing to Itachi however were the elemental techniques they were using with chants, all pointed at him.

He looked down at his sword, and shook his head disappointingly. ‘Just when I’m yet to recover my eyes.’

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He was in a very bad place, special eyes or not, that was something he could clearly see.

“It wouldn’t have gotten to this stage if you had listened to what I was trying to tell you.” Itachi said.

He wasn’t a man of many words so most of the times he spoke extensively, it was logically factual and straight to the point.

The smoldering heat on Isshin’s blade, could be felt by all the Shinigamis around them so they knew not to get close to their Captain. “And why were you snooping around Shinigamis?”

“Information on this foreign world.” Itachi answered. “And as I’ve told you before, even this blade wasn’t initially mine.”

“Right, how awfully convenient.” Though Isshin said that, he was more inclined towards itachi’s story being true. “How long since you arrived in the Soul Society, and what district?”

“69th District, North Rukongai. Around a year, give or take.” Itachi replied.

Isshin sighed before asking. “And I’m guessing you won’t lower your blades and come with us?”

Itachi didn’t answer because his posture was more than enough of an answer for Isshin.

This wouldn’t have been that complicated an issue had it been any other time but the Captain Commander had been strict on his orders for the Captains to unearth the reason behind the recent disappearance of souls and heavy traffic of Hollows.

Isshin didn’t really have the leisure to be as willful as he usually was, more so when the young soul in front of him just quickly liberated the heads of three of his Shinigamis.

Central 46 might bitch about a few rules, especially owning a Zanpakutō that wasn’t legally issued, but Isshin knew he had a full pull to waiver the matter had it just been that, way before it had escalated to the standoff it was now.

‘Not to mention he almost relieved that princess’ precious bodyguard. Grrh, I hate politics.’ Isshin mentally berates himself for how fucked up the entire situation was, all the while Itachi quietly plotted his escape.

‘Not to also mention how close he is to Shikai. No Zanjutsu, Hohou or Kidō; and yet he could hold his own this far, even when surrounded and being pushed back by me.’ Isshin analyzed Itachi’s battle ability, and safe to say he was quite shocked.

‘With this many people surrounding us, he will contain his fire-based attack more conservatively and all I need in response to that is three of the Shinigamis pushing their location to the Captain.’

Itachi stabbed his sword into the ground to the surprise of the Shinigamis who, except a few, thought he was giving up.

Even if he couldn’t use any jutsu, he could still let his Reiatsu flow out of him like he does when climbing trees or walking on water.

Pushing his Reiatsu through the sword into the ground, the ground burst open around the perimeter of the surrounding Shinigamis with spikes of raw Reiatsu like aura blades, forcing them to retreat, even Isshin.

Seeing his chance, he backpedaled to the two nearest Shinigamis who found two normal blades stuck in their chests as Itachi blurred past them.

Seeing Itachi escape, Isshin locked into his bubbling Reiatsu and held his blade forward. He could completely obliterate the area around Itachi with a single attack but he decided against it and lowered his blade.

“Captain Shiba?” Rangiku called out in confusion, seeing how her Captain wasn’t giving chase.

“Did anyone register his Reiatsu signature?” He asked as he deactivated his Shikai.

Thankfully, his ever dutiful Vice Captain replied positively. “Yes, Captain. I did it when you were holding him back after we arrived.”

He nodded. “Good. Run it with the Second and Twelve and see if he was a Shinigami at any point.” He said.

“Yes sir!” She saluted and immediately got to work to contact the 12th Division and handing over the data to the group from the 2nd Division with them.