Inuzuri Mokugeki, of the Menimienai Squad, watched over the town of Karakura carefully.

He was part of a specialized section of the Second Division, composed only of people who possessed no spiritual power. They were a unique squad, in that they were the only shinigami who never attended the Shin'o Academy. After all, without any reiatsu, they would never be able to enter, let alone graduate. Instead, spies from the Second Division were always on the lookout for potential new recruits in the Rukongai. They searched for people who were good at hiding and remaining unseen by others. If they spotted a person who held potential for espionage, they were offered a job.

As his surname suggested, he indeed came from the Inuzuri district, one of the most outermost regions of the Rukongai. He never did possess any strength, physical or spiritual. But he always had a knack for staying out of the way and ensuring that he could keep hidden from those who wished to prey on the weak.

It was because of these characteristics that he was recruited into the Second Division. Upon entering, he finally gave himself the name Mokugeki, meaning "witness," to reflect his new occupation as a spy.

That was the sole purpose of these "powerless" shinigami: reconnaissance and espionage. When it was too risky to send in normal Onmitsukido members, it was the Menimienai who were ordered into the area. No one would bother searching for someone with no reiatsu, after all. Another advantage to the Menimienai was their immunity to starvation. Without any spiritual power, these spies were able to stake out a target indefinitely.

Today, Inuzuri's assignment was to observe the dormant Karakura while it was inside Soul Society. If all went well in the world of the living, his day would be boring and he would have nothing to do except stare at sleeping humans.

But of course, things had to go wrong.

Inuzuri was glad when only two enemies showed up to attack Karakura, but relief turned to terror when he saw who the two people were: Aizen Sosuke himself and his right-hand snake. The spy prepared for the worst and assumed that everyone who had been sent to the world of the living had been killed. But if Aizen and Ichimaru were all that was left of the enemy's forces, then it at least meant that the captains and lieutenants had not gone down quietly.

He noted Aizen's strange new appearance, and how his reiatsu had changed. Like a fingerprint, every being in the afterlife had a unique spiritual identity, and every member of the Second Division was trained to memorize every reiatsu signature they observed. While Aizen's reiatsu continued to be his own at its core, there was something… twisted about it, a feeling that was augmented by the man's physical appearance.

The spy followed their movements carefully, keeping them within his sight. Because he had no spiritual power, he was beneath their spiritual radar. And his training under Captain Soifon ensured that he could move without alerting the other mundane senses as well. He was dressed not in the standard black outfit of the Onmitsukido, but in lighter gray shades, to blend in with the rooftops better.

If one would pardon the boast, he truly was embodying the meaning of the Menimienai Squad.

He was surprised when the two rogue captains encountered a group of spiritually aware and conscious humans. He took no pleasure in seeing his Number One enemy pursue the children, but neither did he feel any compassion. For one, there was nothing he could do to help. Second, years in the Rukongai, and even more missions in the Onmitsukido had inured him to many sights, even ones involving children in danger. And third, he was under strict orders to observe only.

Inuzuri was surprised when he witnessed Lieutenant Matsumoto of the Tenth Division arrive to save the humans (temporarily, at least), only to be dragged off by Ichimaru. Since his mission objective was to keep an eye on Aizen Sosuke, he let them go.

He watched as Aizen toyed with the humans (and the shinigami who joined them) for a little while, until Ichimaru returned, noticeably without Matsumoto in tow. He wondered what happened to her, and again assumed the worst: Ichimaru had killed her.

The spy risked getting close enough to hear the conversation between the two men. He stopped just within earshot; this endeavor was life-threatening by itself, but he felt it was worth it. And his feelings were proven correct when overheard them say they were about to create the Oken.

Since he was under orders to immediately alert his superiors when he witnessed Aizen getting ready to create the Oken, the invisible man prepared to make a quick exit.

During his years as a spy, Inuzuri had learned how to control his expression, no matter what occurred in front of him. With all the prying that was in his job description it was to be expected that there were to be some shocking sights, and he had been trained to mask his emotions. Despite all that he had seen in his career, he could not stop his jaw dropping in shock as he witnessed Aizen's right-hand man have the audacity to stab his boss in the back to his face.

"The only way to beat Kyoka Suigetsu's Complete Hypnosis is to be touchin' the blade before the illusion is cast."

That one sentence was worth twice Lieutenant Oomaeda's weight in gold. It was too bad that information was a bit late in helping the Gotei 13.

Inuzuri watched in shocked fascination and controlled glee as Ichimaru revealed the true venomous power of his God-slayer Spear, killed Aizen, and then stole away with the Hogyoku.

Well, that had been unexpected.

The unseen man spent a few moments thinking about the new development before focusing his mind on what he should do next. The first order of business was to double check Aizen's condition and make sure the man was dead. If he really was, then the next course of action was to follow Ichimaru, in case the snake had only killed his boss so he could have the power of the Hogyoku for himself to fight the Soul King.

He was about to leap down and check the body when he heard a furious roar from the man who should be dead.

That euphoria of victory was replaced by dread as he heard Aizen's voice echo over all of Karakura, and declared Ichimaru's efforts worthless.

The powerless spy did not see the death blow come, but he could detect it when one captain-level reiatsu source suddenly vanished.

He leapt silently from rooftop to rooftop as he tried to regain his view on Aizen, and wondered how the villain had managed to survive Ichimaru's assassination attempt. Inuzuri doubted if even Yamamoto could survive such an attack like the snake's; it did not matter how powerful someone was, if Ichimaru could pierce the skin, his target's life was in the palm of his hand.

The witness arrived just in time to see Matsumoto begin sobbing over Ichimaru's still form (apparently he had not killed her, after all). Inuzuri feared the worst when he saw Aizen begin to lift his sword once more.

And he was as surprised as anyone else when he saw Kurosaki Ichigo arrive on the scene. He noticed immediately that the substitute shinigami was not radiating any reiatsu. Inuzuri had never met the human personally, but all the reports he had read said that Kurosaki's most distinctive feature was his uncontrollable spiritual power.

Inexplicably, the substitute's spiritual pressure was now as absent as his own. Yet from the way Kurosaki carried himself, it spoke of daunting fortitude capable of moving mountains.

Inuzuri could not stop a small grin from forming as he saw Kurosaki take Aizen away. It happened in an instant, but he just managed to witness Soul Society's last hope for victory grab the villain by the face and fly off at supersonic speeds to a more secluded location.

Since Aizen was gone, and there was no chance he was going to be able to keep up with the two demigods, Inuzuri decided that his job here was finished. Time to report in.

"The captain-commander wants answers," Captain Soifon declared as she entered the meeting room, "Inuzuri, your report."

The spy informed his peers what he had seen in Karakura.

"Why is Yamamoto-sotaicho so interested in this case?" asked the Fourth Seat.

"Because of Ichimaru's attempt to kill Aizen, Yamamoto-sotaicho is considering reinstating him to his rank of captain posthumously," Soifon explained.

"That seems rather generous of him," Inuzuri said with a raised eyebrow.

"Some would see it that way," the captain admitted, "But the primary reason is for morale. After Ichimaru had defected, the Third Division had been devastated. By declaring Ichimaru a fallen hero, the Third will gain some self-respect and pride back. But that is still dependent on this meeting. As Inuzuri said, Ichimaru tried to kill Aizen. What Yamamoto-sotaicho wants us to find out is why."

"The guy was a veritable snake," the Fourth Seat said, "I wouldn't be surprised if he did just for kicks."

"Or maybe it was for self-preservation," Inuzuri suggested, "After all, Aizen does not have a good record for when it comes to valuing the lives of his subordinates. Ichimaru realized this, and decided that if he wanted to survive, he would have to strike."

"I bet he just wanted the Hogyoku for himself," the Sixth Seat said, "Didn't you see him take it away from Aizen?"

"It could have just been a way to separate Aizen from his source of power," Inuzuri countered.

"Maybe he's an agent sent by the Zero Division," the Fifth Seat put in.

"Do you know how outlandish that sounds?" Four criticized.

"Well, do you have any evidence against it?" Five protested.

"We don't have any evidence, that's why we're having this meeting!"

"I'm just saying that information on the Zero Division is classified," Five continued, "But it wouldn't surprise me if the Soul King decided to have a spy keep close to someone he knew would rise against him one day."

"Or, maybe he would leave it all to the Gotei 13," Four contradicted once more, "After all, the job of the Zero Division is to protect the Soul King."

"But Aizen sought to replace the Soul King," Five pointed out, "So by acting preemptively, Zero Division would still be doing their job."

"But Ichimaru Gin, of all people?" Six interjected incredulously, "Even if your theory that the Zero Division was involved is remotely true, I don't see him as being a member of the Royal Guard."

"Why not?" Five asked, "Take a look some of the people we have in the Gotei 13; they're not exactly what we'd call normal, now are they?"

"I imagine that the Soul King has higher standards," Four said, "No, Ichimaru certainly did it for his own reasons. Considering his sadistic disposition, I wouldn't be surprised if the sole reason was because it was fun for him to stab someone else in the back."

"I don't think so," Inuzuri disagreed, "For one, Ichimaru told Aizen that he had been planning to kill him for decades; he was simply waiting for the right moment. For another reason, Ichimaru didn't look like he was having fun."

"What, you mean he actually stopped smiling?" Six asked.

"No, it still looked like he enjoyed killing Aizen," the witness corrected, "But to me, it didn't look like he did it for the sake of fun. Enjoyment was a bonus to killing Aizen, not the purpose."

"That sounds like a pretty fine distinction," Four said.

"Sometimes it's the fine details that separate life and death," Five pointed out.

"And sometimes focusing on the details leaves you blind to the broader picture."

"Maybe he did it for Matsumoto."

The debaters ceased their arguments and stared at Oomaeda, who had casually made his suggestion with a mouthful of crackers. The lieutenant rarely gave any input at these meetings, only appearing for the sake of formality. Most of the time, he would just sit back and eat his snacks. Inuzuri had wondered on more than one occasion if the corpulent man even paid attention to their discussions; apparently he had.

Upon noticing that all eyes were on him, the large man defensively said, "What? We know that they were old friends in the Rukongai. The report said that he carried her off, right? And that he lied to Aizen about killing her, right? Maybe he realized that when Aizen won, Matsumoto would die."

The other Second Division officers gave each other puzzled looks.

"Perhaps that might be a factor," Inuzuri admitted, "But I doubt that it's the whole reason."

"Agreed," Four nodded, as did Five.

"You're giving him too much credit," Six disagreed.

"Perhaps not," Soifon interjected.

Once again, the debaters were silenced by their superior officer's comment.

"Did any of you read Hitsugaya-taicho's account of the events during Aizen's betrayal of Soul Society?" Soifon asked.

They all looked at each other guiltily.

"Part of Aizen's plan included that Hinamori-fukutaicho be killed for outliving her usefulness," Soifon started, and her subordinates nodded to show that they knew at least that much, "There was one attempt by Ichimaru Gin to kill Hinamori the night after Aizen's 'body' had been discovered. The report said that he came very close to succeeding, except that Matsumoto-fukutaicho arrived in time to place herself between Ichimaru and Hinamori. That's when Ichimaru left."

"You mean that Ichimaru disobeyed Aizen for Matsumoto's sake?" Six asked incredulously.

"Told ya," Oomaeda smirked triumphantly.

"That doesn't prove Ichimaru tried to kill Aizen for the sake of a woman," Six argued.

"No, but it is more likely than him being an agent of the Zero Division," Four said while giving Five a pointed look.

"Hey, it was just a suggestion!"

"I've heard enough," Soifon declared as she stood up, "Stay if you want to argue about this more."

There was a chorus of affirmatives, and the captain left the room.

Inuzuri did not remain long enough to find out what the officers would do, because he had a question for Soifon. In the hallway, Inuzuri caught up with his captain and called her attention.

"What is it?" she asked coldly.

"May I ask why you called the meeting?" the witness inquired, "I doubt it was because Yamamoto truly cared how people will view Ichimaru Gin after his death; morale or not, he knows that the Third will recover."

"Very presumptuous of you to question your superiors," Soifon snarled dangerously.

Inuzuri was on thin ice right now; fortunately, he came prepared. In the Second Division, there was a currency worth more than gold: quality photographs of Shihouin Yoruichi. Pictures of the Flash Goddess were as close as one could get with bribery on the Stealth Corps' captain. And he had managed to win some of those prized pictures from an agent who worked in the World of the Living in a game.

Smoothly and gently, Inuzuri pulled a small envelope from his robes and handed it to his captain.

The woman took the paper, and extracted the gift inside. She managed to school her expression, but Inuzuri could tell that his tribute had pleased her.

"Why do you want to know?" Soifon asked neutrally.

"Since I was the one saw Ichimaru attempt to kill Aizen, I simply wish to know all the facts of the case I covered," Inuzuri explained.

The petite assassin nodded once.

"It was a favor," she said, "Someone asked me to see if we could discern Ichimaru's motives."

"The identity of this person is confidential, I presume."

"Indeed," was the clipped reply.

"I am grateful for the answer you provided," Inuzuri said as he bowed.

After the Menimienai man had departed, Soifon stalked through the Division to her office, where she would summarize the meeting's speculations.

She was not a sentimental woman, but this person she was doing a favor for was in circumstances all too familiar to her. Soifon knew the how heart-breaking it was to be left behind, and in this one case, she would try at least one thing to assuage the pain for someone Ichimaru had abandoned.

After she finished the report, Soifon would head over to the Tenth Division; Matsumoto may not have asked Soifon to do this, but the stealth commander knew it would be appreciated. While Soifon had the chance to reconcile with Yoruichi, this information would be the closest thing the lieutenant would get as to an explanation for her childhood friend's actions.

Author's Note: "Menimienai" means invisible or hidden in Japanese.

This was written partly because I didn't like how Gin's name was never conclusively cleared in canon. Yes, Soul Society knows that he was killed by Aizen, but they probably assumed that it was just because he had outlived his usefulness, like Hinamori or Halibel. Still, even then, they'll never know exactly "why."

And the idea of a person with no reiatsu taking an active role in the Gotei 13 had been bugging me for a while, and finally found its place here. Inuzuri Mokugeki is the first time I sailed into the turbulent waters of the OC. I realize he's not very interesting and overall pretty bland, but I never intended to invest much in his character; he was created as a way the Seireitei would at least know that Gin tried to kill Aizen.

And just so you know, the Gotei 13 using spies to keep tabs on Karakura Town is head-canon for me, so I will be referencing this one-shot in my future stories.