(This story will honestly make the most sense if you've already watched the Magikano anime series to the end. For those of you who do not wish to do so, here's a quick explanation:

Basically, within the last five minutes of the series, it is suddenly revealed that the characters are all part of a time loop that has lasted throughout the entire series. In fact, if this time loop isn't continued, the demon lord inside of Haruo will destroy both the main character himself, AND the rest of the world.
So, seeking to preserve their brother/man they love (depending on who you talk to), they put forth a great effort and cast the spell, restarting it all. This ends the series.
No attempt is made to STOP the loop. No one points out that if they just keep looping, it's really no different than if the world was destroyed. No one says there might be another way. They just whole heartedly restart the loop so they can live the last year all over again - perhaps with differences, but still without the ability to go forward. ...Yeah, it sucks.
So this is my answer to that. While I don't think I managed to get too good a grip on the characters, I hope it can at least give SOME help to anyone who saw it and felt a need for resolution.
(The twist at the end is merely a matter of personal amusement, and wouldn't exactly be unusual for your average anime anyway. :P ))

Ayumi flushed when she felt the gaze of the others on her, a mixture of indignation and pride keeping her feet rooted to the spot.
"What do you mean, 'no'?" demanded Maika, after a long moment. "Oni-chan is inside of that! If we don't reverse time-"
"Then we won't lose everything we've done!" She glared back at the girl, watching as Maika's furry crumbled into confusion. "I don't..." She hesitated, swallowing as she tried to work past the lump in her throat. "I don't want to lose it! My time with Haruo-san .."
"But Sempai..." whispered Marin. Ayumi glared at her, cloaking herself in anger over embarrassment. She could feel the kitten-panties beneath her skirt straining forward to listen as she moved, making her resist the urge to squirm as she stared the girls down.
"If we reverse time, he's dead anyway, isn't he? The Haruo who we know, the one who spent the last year with us! It's not living if we don't move forward! It's not living if I hate him again, or if we don't know him anymore, or if..." she stopped, trying to form the words properly. "It's not living if we never get to live beyond a year, you idiots!"
"Then you will let the demon lord destroy us?" demanded Hongo. Her voice was indifferent, matter of fact rather than demanding, and enough to make Ayumi hesitate.
She forced the urge down,, determination flaring through her as faced the teacher. "You said we're the girls in his heart, right? So let's strengthen his heart! Even a weakling like him won't fall if I'm there to support him!"
Maika nodded, the others following suit. "Onii-chan…"

Ayumi swallowed down the last of her worries, taking a breath as she looked at her allies. "Then give me all your power, you obnoxious cat!"
She felt the panties moving beneath her as she spoke, the annoying "Yes Ma'am!" working its way through her ears. Then the power was hitting her, a miasma spreading to each side as debris flew towards her. She evaded it, working towards the center, the others imprints to the side of her vision. It was burning through her, the power coursing down her veins just to keep herself from being burned to a crisp. And then she was through, and she was hugging him, his surprised face squashing against her breasts as her legs climbed around him.
She could hear the words "Onii-chan!" taken up and repeated, more presences joining in, then others as well. "Sempai!" and "student council member," and "demon lord," all coming in close, surrounding her.
She ignored it, for a moment, and then embraced it, the power flowing between themselves. She pressed it into him, shivering as she squirmed against her body, filling him with thoughts of her and the others. The mishaps, the erased incidents, the failed seductions, and everything else she could think of alongside the other girls.
She felt something shudder, a white light piercing her, than nothing.

Ayumi groaned, feeling something soft beneath her as she moved, a groan coming from her as the light pierced her eyelids. Normal sunlight, she decided, looking around the glad. The girls were scattered everywhere, and Haruo...
She paused, reaching down and touching the soft thing against her, feeling it squirm as a soft gasp came from beneath her. She turned to face it, face twisting with shock when she saw the former boy, "her" hair falling in waves across her new breasts. The shirt strained against them now that Ayumi was no longer repressing them.
This was going to take a lot more than a magic hammer to fix.