Ayatsuji Yukito Mansion Murders Series – Japanese Locked-Room Mysteries

[✅ May 2026 Update: Fake Sequel Warning]

Recently, a fake sequel to The Decagon House Murders appeared on Amazon Kindle. Strangely, it’s being sold under a different person’s name instead of the original author, Ayatsuji Yukito.

The author has officially confirmed that he has nothing to do with this book and believes it was created by someone using AI. It seems like a scam to trick fans by using the series’ fame.

Please be careful and only buy official editions from verified publishers!

Ayatsuji Yukito’s Mansion Murders Series

*Image source: Pushkin Press – used for review purposes

What Is Connected — and What Is Not

Although this is a long-running mystery series, the stories are not directly connected to each other.

Apart from two shared elements — Kiyoshi Shimada, who appears in every book, and Seiji Nakamura, the architect who designed the mansions where the murders take place — the stories and characters do not overlap.

Each novel tells a completely separate story with a different case, and the series does not follow a continuous timeline.

If we list Ayatsuji Yukito’s Mansion Murders series by publication year, the order is as follows:

Common Settings in the Mansion Murders Series

The Detective Shimada Who Appears Throughout the Series

Kiyoshi Shimada, who plays the role of the detective in the Mansion Murders series, is not a typical brilliant detective.

Instead of standing out as a genius, he has a friendly and easygoing personality that helps him blend in with people around him. Through casual conversations, he slowly gathers information and gets closer to the truth.

He does not feel unrealistically clever or perfect. This down-to-earth style works well with the closed and uncomfortable mood of the Mansion Murders series.

*Image source: Pushkin Press — used for review purposes

The Core Formula of the Mansion Murders Series

Isolation, Serial Killings, and Twists

Every story in the Mansion Murders series starts in the same way:

Inside a sealed-off mansion, completely cut off from the outside world — a classic closed-circle setting.

Once a murder happens, the situation quickly spirals out of control. People die one after another, sometimes several in a very short time. And if you follow the story closely, the culprit is almost always someone you never expected.

Why Reading Order Matters

Similar to Publication Order, but With Rising Difficulty

All books in the Mansion Murders series can be read on their own. However, there is a recommended reading order, which is mostly similar to the publication order.

If you look at the mansion layouts in each book, the difference is clear: Decagon House → Watermill House → Labyrinth House → Clock House, with each building becoming more complex than the last.

As the series goes on, the books become longer and the structures more difficult to follow. Having read the earlier novels makes it much easier to understand the rules, layouts, and movement inside the mansions.

Personally, I think starting with The Clock House Murders and then reading the earlier books might make them feel a bit less impressive.

Things You Should Prepare Before Reading

If You Are Reading a Physical Book

It is strongly recommended to keep bookmarks on:

• the character list, and the mansion layout pages at the front of the book.

You will need to check them often.

If You Are Reading an E-book

Most readers end up:

• saving screenshots of the character list and layouts, and
• going back and forth between pages until they get used to them.

This is especially important for The Clock House Murders, where the character list can be very confusing at first.

* Image source: Pushkin Press – used for review purposes

Who Should Read Ayatsuji Yukito’s Mansion Murders Series

This series is a good fit for readers who enjoy:

• locked-room and closed-circle mysteries
• fast-paced serial murder stories
• mystery novels with clear twists
• visualising floor plans, movement, and space while reading
• a strong sense of satisfaction when everything comes together at the end

Spoiler-Free Summaries of Each Mansion Murders Novel

🏝️ The Decagon House Murders

A group of university mystery club members gathers on a remote island to stay in a strange building shaped like a decagon. The original owner died in an accident, and the building has been left empty for years.

👉 Keywords: isolated island / group stay / strange building / growing tension

🌊 The Watermill House Murders

Deep in the mountains stands a mansion with a working watermill. A man who has lived away from society since a past tragedy meets the suspicious figure of Kiyoshi Shimada.

👉 Keywords: gothic mansion / obsession / past trauma / dark mood

🧩 The Labyrinth House Murders

A famous mystery writer invites his students to his mansion. After his death, he leaves a will stating that his inheritance will go to the student who writes the best novel inside a house filled with maze-like rooms.

👉 Keywords: spatial puzzle / confusion / architectural mystery / Closed-circle mystery

⏰ The Clock House Murders

A mansion filled with large clock mechanisms becomes the meeting place for a group studying paranormal phenomena. During a séance, the building is sealed, and a series of murders begins.

👉 Keywords: time-based mystery / Locked building mystery / complex structure

* Image source: Pushkin Press – used for review purposes

Reading Late, but at the Right Time

I usually read only mystery and thriller novels, so discovering this author so late felt strange at first. These books were published a long time ago, and I honestly wondered why I had never come across them before.

As of now, only four titles in the Mansion Murders series have been translated into English. I sincerely hope that more will be available soon.