In fact, the mentioned red-head did not "get the message" and proceeded to investigate the crates closer. "Hey, this one's got a button on it! I wonder what this button does..." In a fit of extreme curiosity and stupidity Seiichi actually pressed said button.
Immediately the door of both crates flung open and out of each crate a syringe launched at the boys and both hitting them dead center in the arms unloading their contents into their respective bloodstreams.

Seiichi shouted in pain and fell to the ground. "Shit, shit... sorry..." The pain, however, only got worse as the nanites started their work and soon it became so unbearable that slowly his vision faded and before long he passed out.
---

A long while had gone by and slowly but certain Seiichi's senses returned. Nevertheless he felt different than usual. Not different as in worse, but different as in actually better. For starters, he felt lighter and a bit giddy, too. He blinked a couple of times and stared at the ceiling. It was apparent he still lay in the same spot he passed out in. A loud sigh escaped his mouth and this made him gasp. 

His voice was way too high to be his. "Uh, hello...?" 
Yup, something definitely was wrong with his voice. It was all husky and rough, but also way too high pitched to be his old voice. "This is weird... talking to oneself is, too..."
Still this voice... Seiichi groaned and put a hand onto his head, only to find out that his muscular hand had shrunk to a petite, girlish one.
In slight awe his gaze wandered from his hand up his smaller, less muscular arm to his slim shoulders down to a slightly bulged chest, further down to a slim waist and wider hips covered by a pleated school uniform skirt.

"What the hell...? I look like a girl!" Seiichi exclaimed. 
With one hand he flipped up the skirt just to be greeted by a white pair of panties and a suspiciously flat. He brought his hand to his groin and groped it...
Mnnnnnnoooopeee... no male organ present... and it felt very strange... and comfortable... which was kind of scary, actually.
"Frack... I'm a girl?"
Seiichi spotted a conveniently placed smartphone with camera, so he switched it on and took a picture of himself. Then he opened the picture.
[hider=What he saw absolutely shocked him]
[IMG]http://i.imgur.com/PUBZecC.png[/IMG]
[/hider]
He looked like a freaking cute girl! He even had two ribbons that bound his two new pigtails. Or was it she now? He looked at the picture again. Yup... she.

[b]She[/b] took out her Student-ID-Card and looked at it. Back at her stared the same girl as on the selfie named "Sayuri Nakao"
"This day's gonna suck..."