A while ago I said that the anime Kyousougiga is impossible to describe, but it turns out that it isn't, because meganbmoore has done so.
A few centuries ago, there was a monk named Myoue who had the power to bring anything he drew with his own blood to life. Sometimes people said "I want to see an oni!" so he made them an oni and the ungrateful people ran away screaming that he was trying to kill them. One of his creations was a black rabbit named Koto. Koto fell in love with Myoue and the Bodhisattva granted her a human body so that she could confess her love. Myoue found this a tiny but disconcerting, but didn't seem to have many issues with a pretty woman now hanging around his house. Eventually, Myoue brings home an orphaned boy named Yakushimaru, who they adopt as their son. They decide Yakushimaru needs siblings, so Myoue creates Kurama, who appears to be a normal human boy, and Yase, who appears to be a little blond Victorian girl who just happens to also be a demon. People off in the capital start getting a wee bit freaked out by all this and so the family leaves Japan and goes through a looking glass into a mirror Kyoto where no one dies and nothing changes. Eventually, Koto's deal with the Bodhisattva ends, and she and Myoue leave Kyoto, leaving their devastated children behind.
Fast forward to the present, and the children have grown up-Yasu is literally an adult version of her childhood self, Yakushimaru has become a (far less than pious) monk and renamed himself Myoue, and Kurama now looks like an old man in a child's body. Theoretically, the three rule the mirror Kyoto together, but it's mostly just Kurama running things, and all three are still missing and looking for their parents. Things have been going on forever and ever like this when a young girl named Koto accidentally stumbles into mirror kyoto with her two spirit familiars, who she calls her brothers. Koto has a ginormous (but customizable!) see-through hammer and is searching for a special rabbit that she has to find before she can return home. Except she has no idea how to get there, and so she and her brother's move into Yakushimaru's temple. Much to his consternation, they are delighted to learn that the temple repairs itself and test it's limits every five minutes. That's actually not an exaggeration. No one (including Koto) knows if the new Koto has a connection to the original Koto, though it's theorized that she's either a new child of Myoue and Koto's, or possibly the original Koto reborn. There's also a teenaged otaku mad scientist with a couple hundred white-suited goons who are utterly devoted to her. She sometimes rampages through the city when she loses things. She also has a long-suffering assistant who either really really likes her, or is a secret masochist. Or both.
This plot description, incidentally, will in no way prepare you for the pure, high octane crack that you will be engulfed in mere moments after starting the series.
The series hops all over the place to the family before going to mirror Kyoto, the children dealing with the loss of their parents, the present after the new Koto arrives, and the new Koto's own past. There are helpful little "past" and "present" notes each time the setting changes, but the series, apparently knowing that the audience will look at 80% of the plot and go "WHAT IS THIS I DON'T UNDERSTAND WHAT'S HAPPENING," chooses to focus on the dynamics of the various forms of the made family in both the past and the present and people's feeeellliiiinnnnggggssss about their parents and their siblings and the things you put up with because you secretly love your siblings and when you have grudges against them and whatnot.
It's absurd, confusing, touching, sentimental and utterly shameless[.]