I have 3 one shot ideas! I may make more, but I dunno what kind of genres you guys would be willing to read on here.
First off, let me ask you what genres of the following would you be interested in reading?:
Action
Mystery
Psychological
Adventure
Romance
Comedy
School Life
Drama
Fantasy
Genderbender
Shounen ai
Horror
Historical
Sports
Sci-fi
Martial Arts
Tragedy
You're welcome to combine them! Never gonna do a pure action manga or anything, that's just boring.
Now, here are my concept ideas so far:
Concept 1: Playing a game to defeat the CPU. Only 9 game hours before CPU ends the game. Each player has 9 lives except for the CPU.
Genre: Psychological, Mystery, Action, Romance (just a bit), Drama, Sci-fi, Tragedy
(Extra Question for the above: Should 9 even be associated with the game?)
Concept 2: An average high school senior is suddenly kissed by a famous idol/model on the day of his graduation.
Genre: Romance, School Life, Comedy, Shounen ai
Concept 3: In a world of ninjas life is still pretty the much the same as a world without ninjas. Everyone goes to school to become ninjas in certain fields and subjects. A medical ninja, a war ninja, a idol ninja, etc. They also have lots of different clubs for ninjas. One of the ninja students (main character) tries her best to maintain a fairly unpopular club called the ‘ghost hunting club’. It’s not very popular because nobody has found a ghost and it’s just a hang out club. But one day the main character finally catches a ghost. But it’s actually the other way around, the ghost, instead, possessed her. Now she must fulfill the needs of the possessed ghost so that they may finally rest in peace.
Genre: Martial Arts, Tragedy (not really, but if we're talking about how a person died, it's kinda tragic), mystery, fantasy, historical (ninjas are historical! XD), action, romance (maybe?)
I might make a promo pic for each for people to decide better. What's the big deal? I am LAZY I can only do ONE one shot at the time and I'd like to choose a good one that people want to read so I can keep going!
My longest one is the first one, the other two are fairly short.
I will most likely have more than 3 concepts for you guys to choose from. I want to make one shots including some of my OCs.
I might make a one shot for my fighting characters, I just need to look over that old stuff.
Also, concept 3 was a really old idea I made up when I was little based on what I thought Naruto would be about from the pictures I saw! XD
Bye-bye! Hopefully I can come up with some more concepts! 
