Takoha Tsutomu, fresh off art school, is an aspiring picture book author who can't find anyone willing to publish his works because of his self-indulgent, dark illustrations. While on his way to be rejected by yet another editor, he meets a little boy named Rokurou who's moving in next door along with his father. Sounds pretty normal, right? Except that the house next door is Sou-Bou-Tei - a mysterious mansion that has towered proudly over the Tokyo district of Numanakarai since the Taisho period. Legend has it that those who enter either never escape, or leave having experienced horrors untold, and with the desire to take revenge... But those are just silly stories, and it's not like they matter to Rokurou, who won't even live in the mansion proper, but in the small house meant for servants. Takoha and Rokurou part on friendly terms and go on living, secure in the knowledge that the gossip is nothing but a bunch of lies.
Except that when the evening comes, Rokurou's dad is dead, Rokurou himself is screaming about man-eating houses, and the entire district gets bombarded with the explicit goal of destroying Sou-Bou-Tei... which gets out of it completely unharmed and still stands unscathed among the ruins of other, not so fortunate houses.
And thus begins the story of Takoha, Rokurou, and many others whose lives became, by accident, by interest, or by order, entangled with the fate of the titular mansion. Although they are all completely different people, there is one thought that connects all of them:
Sou-Bou-Tei must be destroyed!
This series provides examples of:
- Ascended Extra: During her introduction, Yadogiri seems like a one-off character whose only purpose is yelling at Rokurou, but once the invasion on Sou-Bou-Tei starts, she becomes part of the core cast.
- Battle Couple: The Maag couple. She has pyrokinesis and burns the enemies, he's there to push her wheelchair where the enemies are.
- Bizarrchitecture: Sou-Bou-Tei itself. Stairs and doors that lead nowhere, hat hangers that are too high to reach, peepholes that show a solid wall, closets and shelves that are completely unusable...
- Body Horror: Deido is often drawn with strangely elongated body and makes poses that are impossible to pull off for a normal person.
- Chance Meeting Between Antagonists: Takoha stops for a friendly chat about art with a strange guy, fully unaware that he's talking to Sakamaki Deido, the creator of Sou-Bou-Tei and his enemy.
- Character Death: Surprisingly averted for the most part - while some characters, most notably the oldest Kirita sister, do die, overall there's much fewer deaths than in other series by the author.
- Connected All Along: The Maag couple destroyed the house where Augusto's father died and which he desperately wanted to do research on. More importantly, Oujin is Deido's errand boy.
- Driven to Suicide: Deido's sister after her parents separated her from her lover. Since she converted to Christianity (in which suicide is considered a sin) under his influence, she couldn't bring herself to do it and asked Deido to kill her instead.
- Freudian Excuse: Deido wants to take revenge on humanity after it didn't appreciate his art.
- Guns Are Worthless: There are plenty of creatures in Sou-Bou-Tei that are completely immune to guns. They're still pretty useful against more human enemies, though.
- Humans Are Special: Many supernatural characters comment on this; more specifically on humans having feelings and emotions (which they themselves lack).
- I Am Not Pretty: Not only does Kaerikuro not think she's pretty, she convinced she's completely hideous. It's all thanks to the cult leader who raised her - she convinced her that she's so ugly no one could stand looking at her (lest she had the confidence to leave the cult and live by herself) and that she should cover her face at all times (lest someone fell in love with her and stole her away).
- Laser-Guided Amnesia: The aliens are capable of invoking this on their victims; most notably, all the prime ministers forgot that they were pulled inside the painting at some point and that the paintings are dangerous.
- The Load: Every now and then someone complains that Takoha is this, as he's the only one who has no powers or training that would justify his going to Sou-Bou-Tei, even though he proved he can be useful more than once.
- Long-Lost Relative:
- Kaerikuro is Seiichi's lost sibling.
- Oujin is the Kirita sister's father.
- Mercy Kill Arrangement: The Maag couple asks Augusto to kill them if they get pulled into a portrait. He refuses.
- Poor Communication Kills: Barely averted. Our heroes didn't listen to Kurenai warning them that Deido's death will open all the passages permanently and were this close to dooming the world as a result. The invaders invoked this on purpose, knowing that no one will listen to Kurenai when she attempts to defend their mortal enemy.
- The Reveal:
- Seiichi spent decades on another planet fighting with aliens who tried to destroy it.
- All the occurences inside Sou-Bou-Tei are caused by the aforementioned aliens who are using the pictures to invade the Earth.
- Seiichi's lost sibling is Kaerikuro.
- Oujin is the Kirita sisters' father.
- Samus Is a Girl: Seiichi's lost sibling, Makoto, is actually a girl. Specifically, Kaerikuro.
- Serial Killer: Deido used to lure women into the mansion to play the part of a bride, after which he strangled them and left them to rot.
- Spirit Advisor: Seiichi's alien grandpa likes showing himself to people on the verge of death and delivering exposition.
- Super-Senses: The Kirita sisters may have a greater sense of sight if one of them receives the others' pupils.
- Values Dissonance: Invoked with Zanka, who, coming from the Taisho Era, has quite different values than characters from the modern times.
- Villainous Rescue: Deido saves Kurenai when Oujin and Shino want to kill her. Of course, that's exactly what they expected.
- "Well Done, Son" Guy: Augusto's whole motivation in life was wanting to gain his father's approval... except that said father died when he was still a kid.
- Would Hurt a Child: Deido will get rid of anyone who interrupts his work, and children are no exception.
- Year Outside, Hour Inside: Time flows differently inside the Sou-Bou-Tei; those inside often feel like only a few hours have passed while in reality it's been days, years, or even decades.
