Of the several hundred policies applied to the Gotei 13 during its centuries-old existence, the single most popular one was that which dealt with diversity. Becoming a fully fledged Shinigami was no longer out of reach for that unfortunate few who could not afford to pay for their Academy training or trace their noble lineage back at least nine generations. The interview process, which had formerly consisted of name-dropping and little else, was completely revamped to include a close analysis of exam reports, personal statements from each candidate and, failing everything else, a series of questions exploring how the interviewee would cope with certain scenarios prevalent within the thirteen squads.
Naturally the older members of the Gotei 13, who were used to accepting students of noble birth into their squads without question, were quite taken aback by the new rules and regulations. To them each new recruit looked more ridiculous than the last. They whispered amongst themselves that to enter the 13 squads all one had to do was produce a worthy sob story. Naturally, General Yamamoto (who had himself benefited from diversity policies many years before) got tired of listening to their squawking and created the Honour club. The Honour club, named by its members was the midpoint between Central 46 and the existing Men's club and gave all of the older members of the thirteen court squads the opportunity to discuss important matters amongst themselves and bring them to his attention should they wish it. Despite the fact that the club itself came about as a result of new diversity policies following arguments in the Central 46 that the elderly felt they were not being listened to by their sprightly squad mates, the Honour club was an unforeseen success with members having regular meetings and handing in letters voicing their concerns to Yamamoto every couple of weeks. When he elected a blind captain, he immediately received a letter from them begging him to rethink his decision. If the man could not see his subordinates' faces how could he properly judge their character(1)? When he elected a non-humanoid captain he received another letter, asking how he could justify the terror it would inevitably cause the man's squad.
Kusajishi Yachiru, lieutenant of the eleventh squad, frequented their letters of concern. Each letter made the same point - that Yachiru was only a small child, the smallest that had ever set foot within their borders and her presence within the thirteen court squads was unashamedly cruel. Yamamoto read all of these letters and breathed exasperated sighs. He could not deny that upon first meeting her he himself had been uneasy. He had met many children her size at the side of battlefields, mourning their parents or hiding from hollows. He had planned to say no himself but he had also been painfully aware that the new Kenpachi would not agree to become captain if she was not permitted to be his lieutenant. Considering the previous Kenpachi was in no position to reclaim his post, Yamamoto had to rethink his strategy. He interviewed Yachiru separately to Kenpachi, with a focus on her mental health and physical strength. Both far exceeded his expectations and, while he was a little irritated that she had not entered his realm through the usual methods, he could not deny that she was more than qualified for a lieutenant position. He repeated these facts over and over again in his replies to the Honour club but it seemed that no matter how many times he repeated himself his message went unheard. With half a mind to keep himself at ease and the other to quieten the Honour club up he instated Yachiru as the head of the Women's Association and ensured she saw a military counsellor every few months.
Yachiru always responded positively to the counselling (out of adoration for the bowl of sweets that her counsellor had on their desk more than anything else) and no one could dispute that her role as Women's Association president suited her perfectly. Even the Honour Club could not deny that Yachiru behaved as if she did not notice the physical differences between herself and her squad members, much less that she loved sweets more than saké.
In actual fact Yachiru had noticed the differences. She noticed that strangers patted her on the head upon introduction rather than shake her hand. She noticed that the furniture in her personal quarters and her Shinigami robes had to be specially made and, unlike the adults in the Women's Association, she could not find any spares in the eleventh squad barracks that fit her. She also noticed on several occasions that the other members of the Women's Association preferred visiting onsen baths to making mud pies as part of the Christmas celebrations.
You might think that Yachiru was saddened by this, that she constantly felt left out. In fact this was far from the case. Yachiru had no rivals to speak of and all of the sweets and treats in the thirteen squads were hers to coax out of everyone's pockets. Yachiru revelled in her unique position as the youngest member of the court guards and told anyone that would listen that she would not change that for anything.
Well, almost anything.
The thing Yachiru never mentioned to anyone else was that there was just one thing about her unique position as the smallest Shinigami that saddened her. As the president of the Women's Association she soon discovered that a lot of the issues and discussion topics brought up at meetings were things she did not understand. She had no experience of being leered at by men or her robes being too tight around her bust. What's more, she certainly did not understand why it was that at certain times of the month her older counterparts seemed to have more issues with the male Shinigami than usual.
She brought up several of these topics on the occasions that the General asked for full feedback from the Men's and Women's association and each time she was very aware that she did not understand what it was she was asking for. She knew that Unohana and the rest of the fourth squad probably had the answers, but she prided herself too much as the eleventh squad lieutenant to bother asking them. What's more, she never brought up her curiosities at Women's Association meetings, instead asking Kenpachi whenever she had the opportunity. She was quite disappointed to learn that he didn't know very much about women either, except an odd little story told to him by the original Yachiru about swords and scabbards.
The last thing Yachiru wanted was to do her job as president badly and she decided to take matters into her own hands. If she did not understand what it meant to be a woman, there was only one feasible option. She would have to become one.
And so it was that Yachiru devised a plan to get exactly what she wanted. She knew that visiting the fourth squad was a complete taboo amongst the other members of her own, though she felt that sneaking into their barracks and stealing from them did not exactly count as visiting. Each night, for a week before her scheme was to take place, she drew a map of the position of each of the thirteen squad barracks in wax crayon. She did not mention her plan to Kenpachi, not because she thought he would not help her, but because she wanted it to be a surprise.
When the day finally came, Yachiru pretended to fall asleep, all the while waiting for Kenpachi to. When the sound of his guttural snores reached her ears, she pulled a mask over her face, grabbed her map and crept out of the barracks. Everything seemed to go according to plan - the streets were all but empty and even the sentry guards of some squads had fallen asleep. While Yachiru was very experienced when it came to sneaking past them, she was so excited about surprising everyone that some of her footsteps were not quite as silent as they could have been and at some points she even giggled out loud.
She reached the fourth squad faster than she had at first thought and patted herself on the back for her speed. She noticed that it looked a lot different in the dark and crept inside, keeping an eye out for the laboratory sections. She was not familiar with the layout of the fourth squad, so ended up getting lost a few times before finding the section she wanted.
The fourth division laboratories were larger than she had expected, with entire display cabinets full to the brim with vials of unidentifiable liquids and pickled creatures. There was an odd smell to the place, though not entirely unpleasant, seemingly coming from a device that resembled a cauldron in the centre. It seemed that somebody had been doing some experiments only recently, as the cauldron was full of a strange liquid that glistened ominously whenever the light hit it.
Yachiru climbed to the top of each display cabinet and rifled through all of the vials, looking for something that would transform her into an adult. Each of the vials had a label on, with words of varying lengths scribbled onto them in spidery handwriting. None of the vials had anything relevant to her own situation written on them.
A little way behind her, isolated from the others, was an older looking display case, full to the point of bursting just as the others were. The vials inside this particular case were coated in such thick layers of dust and cobwebs that their contents were obscured and their labels difficult to read. It was the last case in the room and, failing to find anything in the others, Yachiru wandered over to that one. It was slightly ricketier than the other ones and as she climbed she felt it shifting under her weight. She gripped on twice as tightly and made her way to the handles, using all of her weight to pull open the glass doors of the case. As she opened the first door, a cloud of dust emerged from within, filling her eyes and nose and causing her to sneeze. As she did so, her entire body shook against the case and she lost her footing, leaving her dangling from one of the shelves.
Yachiru shut her eyes so that she didn't see how far it was to the ground and tried to better her grip on the shelves, scrambling her legs and feet against the other shelves to regain her footing. She brushed against several vials during this process, all of which trembled at her touch and threatened to fall. She loosed one hand from the shelving just in time to catch two of the three bottles that threatened to fall at her touch. The third, labelled 'Kitty whiskers', carried on falling until it landed in the cauldron below with a loud 'plop', followed by a hiss as the two liquids mixed into one.
Yachiru breathed a sigh of relief, as she could not think of anyone that would want a vial called 'kitty whiskers' and positioned the vials in her grip back on the shelf. Finally regaining her grip, she climbed to the top of the shelf and examined the vials. The third or fourth one she came to seemed to be the one she was looking for. The liquid inside it was a strange amber shade and, while the label was smudged and she could not read its full title, she could read that it began with 'gir' and was a transformation formula. 'Gir' must have been short to 'girl to woman' and she placed the vial inside her robes before attempting to climb down. The case could not so easily hold her weight on the way down and it threatened to tip as she moved, finally caving as she reached the lowest shelves. Yachiru jumped to the side as it crashed the floor, vials smashing everywhere and sparks jumping as some of the liquids mixed into one.
Yachiru was not sure if she had ever run so fast as she did to escape the fourth squad that night, the stolen vial clutched tightly in her hand. Kenpachi was still snoring when she returned. Giggling under her breath, Yachiru tucked herself up in bed before unscrewing the top of the vial and swallowing it all in one gulp.
The next morning, Yachiru drifted out of sleep to discover that Kenpachi was still snoring and sunlight shone through the windows. She felt somewhat drowsy, but as she remembered what she had gotten up to the previous night, she immediately found the energy to jump to her feet. She was a lot taller than she last remembered and her head bumped against the ceiling.
"Ken-chan!" she shouted gleefully, rubbing her face against Kenpachi's sleeping form. "KEN-CHAN!"
Kenpachi stopped snoring and grunted awake, staring up at the new Yachiru for the first time.
"Hey, Ken-chan!" said Yachiru. "Am I pretty?"
Kenpachi's immediate response was to reach for his zanpakuto and jump off the bed.
"Ken-chan, what are you doing? It's-"
"I don't know who you are, or why you ate Yachiru, but I've been looking for a good fight!"
Yachiru was confused by his words. Didn't he recognise her? Was she ugly? It was only as she ran out of the room to escape the wrath of his sword and caught her reflection in the lake outside that she understood. She had transformed, that much was true, but she had not transformed into a woman as she had hoped.
That same day, Kurotsuchi Mayuri, captain of the twelfth division and research department, discovered something similarly irritating in his own barracks. It appeared that there had been an intruder during the night who had ransacked the place. Curiously, nothing had been taken save for just one of his formulas - number seventy six, 'Giraffa Camelopardalis' - a special blend created with the intention of transforming whoever drank it into a giraffe. It was one of his earlier creations and practically useless so he could not understand why someone had bothered to steal it.
It was several days before Yachiru realised that she had not stolen anything from the fourth division but, thanks to her terrible sense of direction, had gone completely the wrong way and entered the twelfth division instead. It was several weeks before the spots disappeared from her skin and she returned to her usual self.
One useful thing did come out of the entire experience, however, and that was that for the first time whenever the other members of the Women's Association mentioned how annoyed they were by the unwanted advances of men around the thirteen squads and how their robes didn't fit them properly, she understood exactly what they meant.
Or at least, she thought she did.
(1) Granted, Yamamoto probably should have listened to that one.