I have a TON of anime ideas.
The most current one is that of a new witch in a
Urban Fantasy setting. Containing a lot of half breed characters with a wide variety of powers, Loads and Loads of characters, Magical badasses springing from where they are least expected, a lot of curb stomp battles as well as underdog victories, and last but not least a good sense of humor. I'm thinking a webcomic is more of a better idea for this but I so want to make an anime.
For this idea though I already have a list of characters, lineages for most of them, backgrounds, motivations, villains, encounters, and in some cases even brick jokes.
My second idea (which may be integrated to the first) is another Urban Fantasy about a duo of necromancers, a brother and sister. The sister (currently named "Mort") is more of a sentient preserved zombie with necrotic powers due to an accident and her brothers quick thinking. Since any damage can be easily fixed she develops a disregard for her own safety that drives her brother mad since he hates grave robbing parts for her.
The brother (currently unnamed) is a bit more interesting structurally. He had lost one of his arms in the same accident his sister was in and replaced it with a mechanical construction that uses necrotically controlled parts of his own arm instead of servos and motors (since he hates grave robbing). He later builds a small (car sized) mecha for his sister to use through similar methods.
There is also a third character who I have (In universe, Mort has) dubbed "Red". He works for the government and is tasked first with eliminating them then, after elimination fails spectacularly, observing the previous pair. He has a pathological fear of Mort after the first meeting in which he blows off half her jaw only to have her pin him down and yell at him (with only half a jaw), spewing blood and spit everywhere. Then she accidentally sneezes and coats his entire torso and face in blood. Eventually I plan on him succumbing to stockholm syndrome. Yes he is the but monkey of the series.
Also there are a group of zombie/necromancer slayers. A modern day paladin and healer. A gravedigger who is the brothers nemesis. And a few other necromancers of varying alignments.
This one is a lot more "Dark powers, Good People" and mistaken intentions sprinkled with a lot of comedy or at least attempts at comedy.
I also have older more fleshed out settings and characters somewhere in my brain but it would be hard to post a simple synopsis of them.