Unsurprisingly, it was Asuna, the first student in Negi's class to find out about his being a magic user, as well as his closest ally. He also lived with her in the dorms as well. Though instead of greeting him with a friendly "Hello", Asuna looked at the magic circle in the distance and walked right up to Negi, staring him at the face. Her expression on said face was that of an annoyed one
"You were serious about it, weren't you?" questioned Asuna, who then stepped back and sighed. "You always like to go head first into things, typical of a runt."
"But Asuna-san, this magic could come in very handy in the future", Negi defended himself. "What if I were able to make your, as well as everyone else's, Pactios stronger by augmenting your size in the process? Surely that would be of help in the future."
"But the thought of a 'magic growth spell' sounds like something out of a science fiction story, not a magic book", replied back Asuna, still fairly disappointed that her own teacher would try such a thing. "I can't believe you would try such a thing."
"At least let me try it on this pebble", asked Negi, staring at Asuna somewhat with a puppy-dog eyed expression. Asuna tried to resist it as best she could, but found out she couldn't last for long. She eventually caved in to the younger boy's request.
"Sigh...all right. But I want to stay here in case anything happens, Negi."
"Alright then, Asuna-san. Stand behind me and watch me make this rock grow to a the size of a boulder."
"I suppose if it DOES work, it would be fairly neat", said Asuna, now stepping back about 10 feet from the circle, but still within talking distance to Negi. "All right then, Negi, let 'er go!"
Negi then lifted his staff vertically in his hands, the staff facing directly in front of the circle. He then began the chant:
"Incresco Tantus!"
And with that, a light flashed from his staff, successfully causing the pebble to grow. Unfortunately, Negi's aim with the spell was off, and in addition to the pebble's growth, he made a much wider radius of objects grow around him grow, including a buried can of soda in the dirt, several other assorted rocks, and even Asuna herself! As soon as the circle engulfed the teenage girl in the lightly colored light, it disappeared completely.
"Asuna-san!!!" Negi exclaimed, running to his student. "Are you feeling all right?"
Asuna looked at her body, wondering if anything happened to her. She was relieved to find out nothing was different than it was a minute ago, "I feel fine, Negi. But I wonder if the circle did make all those things grow..."
Asuna then proceeded to pause, and gulped, continuing with "I wonder how big I'M going to get."
"Well, if you were to grow, you would've done so by now, would you know?" wondered Negi, looking at Asuna for any differences in height.
"Yeah, you're right", smiled Asuna. "I don't feel any different at al...hmm? What did I just fell right now?"
"Asuna-san, your...chest. It got bigger."
"Negi, you're only 10 years old", grumbled Asuna, annoyed at Negi's gawking at her breasts. "You're too young to talk about bre..oh hey, you're right!"
That wasn't the only thing that grew. So did Asuna's hair, arms, legs, and backside. Even the bells in her were starting t grow. And all the while Asuna looked worried, as if she heard a bear rustling in the middle of the woods. Thankfully her clothes grew with her, unlike some of Negi's other spells in the past, but this was still a big shock to the girl. Only a couple minutes later did she finally growing.
"Well I guess it did work. See?" grinned Negi. Asuna would normally at this point yell back at him, but she felt so confused and scared by her height that she could barley talk. Negi noticed this too, walking up closer to Asuna to try to talk to her. Asuna herself proceeded to sit down on the ground, kneeling, noticing the much greater size of scope between her and her teacher. It was almost like comparing an adult to a baby.
"Negi", a worried Asuna said outloud, unsure of whether to cry or yell at Negi. "This is...really weird. We have to fix this NOW before you get caught!"
"You're right, Asuna-san", Negi said in an attempt to comfort Asuna. "I can fix it. I've done it before." His energetic spirit helped made the 20 foot-tall Asuna feel a little better, and with it she then proceeded to stand back up.
"Who knows?" asked Asuna non-rhetorically, attempting to smilee. "This could be like the age pills and wear off in a while. Maybe I should do something to celebrate this temporary mini-giantess spell."
"Like what, Asuna-san?" Negi asked his student.
"Well.....um....I have no idea", Asuna laughed in a somewhat nervous tone.