Okay, so both of these ideas stem from the idea of corrupted magical girl type things, like that madoka magica show I haven't actually watched before, but not that. I probably should for future reference on this sort of thing, but then I might be biased or draw ideas off of it and I don't want that. Anyway, here's the first idea.

The world is corrupted, starting from when Japan developed a bomb made out of some unknown substance they discovered. They used it on the United States during World War 2, July 4th of 1944 to be exact. Some sort of mutating corruption spread across the continent rapidly. Whenever a person died, they would mutate into a creature of complete randomness. Their shape, their powers, their actual appearance, it was all changed for the seemingly random. It wasn't avoidable, either. When a person died, no matter how, if there was a body left, they would start transforming. They had no intelligence, though. They were mindless, feral creatures. Zombies, for lack of a better name, though people just took to calling them "the corrupted". If that wasn't bad enough, living people that touched the corruption would be corrupted all the same, though with their intelligence and desires intact. The "intelligent corruptions", or "Smarts" as some people called them, were far more dangerous. They made plans. They ambushed people, cut off corridors, worked together, made maximum use of their various unpredictable abilities. They were predictable in one way, and one way only; They always had the desire to return to where their previous selves lived. A person that left town and got corrupted would soon attack their town. No matter how well hidden they were, one person slipping up would lead to the corrupted knowing where they were. Nowhere was truly safe in corrupted land.

At the same time, people living in corrupted lands sometimes developed strange abilities of their own. Children, especially, were susceptible to these natural mutations. Enhanced natural ability, powers, minor physical mutations, that sort of thing. At first it was thought that the children were born corrupted and they needed to be killed, but scientists soon discovered that this was only partially right. The children had a small amount of corruption in them. The corruption was a small part of their DNA, even if they were completely normal children. The world was quickly becoming what was once considered high fantasy, as even magical items could be found in places of strong corruption. The corruption itself seemed to be the source of these fantasy-like results, and no one but the officials of Japan knew why.

Speaking of Japan, for the first five years of this horrifying situation, they were the only ones unaffected by this. Even their own allies succumbed to the corruption. Japan was the only government left in the world, and those that could, fled to Japan for safety. They had some sort of rune system that could hold back the corruption. Sigils that, when drawn on the ground in a shape, could create a barrier in that shape. They had to be renewed quite often, and there were plenty of people dedicated to keeping them up to date so that they could survive. Everything was fine and dandy in the land of the rising sun, up until the explosion. It was August 27th, 1948. Some sour saboteur decided that if Japan was going to subject the rest of the world to this horror, they should be too. They found the factory where the corruption bomb was first created, and blew it up. The corruption spread every which way, and the barrier kept anyone from escaping. Japan was the last to fall, and is filled to the brim with Smarts to this day. Entering Japan is suicide.

We begin in late August, 2017. Our story takes place in Europe/Asia. Old world maps identify this land to previously be known as Georgia. One of the few lands where the number of Corrupted are manageable, and children can live to reach their teenage years. Since the explosion, there were unprecedented side effects. The corruption reached everything. The sky, the sea, the very fabric of reality, it was all twisted. The grass became purple. The sky became foggy with a purple mist that just hangs high in the sky, blotting out the sun. Light still comes through, oddly enough. In fact, the world is in a state of perpetual dusk-dawn time, as if the sun never sets and the moon never rises. No one can figure out why this is. Time is indeterminable, and people that have kept up with the days through the years find it to be somewhere in late August, but it is impossible to confirm that anymore. Diseases might be the one thing more common than the Corrupted. Many villages have obtained the knowledge on how to replicate the barriers by now, though they can only do so sparingly, as it requires chalk and placed stones buried almost entirely in the ground. The barriers themselves last until the sigils are smeared, though for some reason that same side of the stone can never be used again for a barrier. Vaccines have been created against the corruption, and they work fairly well against basic corruption. Touching the grass wont corrupt you as long as you're vaccinated, but touching pure corruption will convert you, and Smarts make it a point to corrupt as many as possible in this way. Most villages have hunter, people that are sent out of the village to find supplies for the village. Many do not make it back, regardless of their innate ability. The random nature of the corrupted means that it is impossible to plan against them, and what works great on one might not work at all on another. 

Reality is constantly twisting. Time is impossible to be certain of. Rumor has it, a young woman fell from the sky in a nearby village, and a hunter of the town has taken her in. She does not know how this world works, nor does she understand fully the horrible state the world is in. One thing that sticks out about these rumors, is that since she appeared, patches of green grass have appeared where she resides. Land that can be used to grow food. If these rumors hold true, this is the place to be. The hunter is supposedly incredibly powerful, having protected this village single-handedly, and on top of that there might be someone there that can stop the corruption. And so, you are traveling there to see for yourself. On the road, you found a few other brave travelers looking for answers, and that is where our story begins.

Alright, so this is my first idea. I prefer this one more, since I have way more already thought up for it, and I can do more with it. Your characters will be travelers looking for this rumored healer woman, for one reason or another. You are united in your journey to find safety, the one thing never promised in this world. Magic powers exist, and where the "magical girl" aspect comes in is, you guessed it, the woman is a magical girl stereotype. She's going to stick out like a sore thumb, but she might be able to cure the world. Or, even better, teach others how to cure it with her. This part is up for changing, it's just what inspired the original idea. 
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
My next idea is a much more simple one that sort of came off the first one. It's a basic magical girl show at first, (boys allowed! But, naturally, the leader has to be a girl.) up until one of the members of the group jumps through the magical doorway the monsters come in from, confident his teleporting ability can get him out of this situation once he investigates it for the group. His mind is lost to the massive shapes before him that his brain cannot comprehend, and the generic home base Zordon-type character can feel the mental powers of the monsters seeping into their mind. Everyone of the group can hear it in their head as well, as the home base is lost to whatever took their teammate. Now, they need to figure out what is going on, get their powers back, and stop the monsters as their duty was originally set to be!

Yeah that's all I've got for that one. It needs more fleshing out if I was gonna do it.

Suggestions are greatly appreciated, I probably wont even attempt to make either of these until after finals, which are this week for me. So, yeah.