100かいだてのいえ

100かいだてのいえ (roughly “The 100-Storey House”) is a picture-book series by いわいとしお (Toshio Iwai), published by 偕成社 (Kaiseisha) since 2008. Before turning to picture books he was known as a media artist, making interactive works, television programmes and art software. In a note on the publisher's site, he explains that the first book grew out of his elder daughter's struggle with numbers in her first year of school.

There are currently six main books, each with its own hero and world: a house reaching into the sky, one underground, one under the sea, one in the sky, one inside a forest tree and one in a marsh. Each stands alone, so there is no need to read them in order.

A book that opens upwards

The series is defined by how it opens: you turn the pages upwards, so each spread becomes one tall, narrow picture, like a cross-section of a building. Readers follow the hero floor by floor; every ten floors a new group of residents appears, and each floor carries a small floor number.

All six main books share the same format — 22 × 31 cm, 32 pages — and the publisher's age label is 「3歳から」 (from age 3). If you are new to the series, it is easier to look at held upright on your lap than lying flat on a table.

Why this series is special

In reader comments on 絵本ナビ and in the letters shared on Kaiseisha's pages, the favourite feature is the feeling of climbing up (or going down) with the hero; many children trace the stairs with a finger as if solving a maze. Every floor is drawn individually and packed with small details — furniture, food, games — so each re-reading turns up something new.

Numbers arrive naturally: counting floors, guessing who lives in the next ten, comparing one home with another. The publisher says it has received many messages from families whose children learned to count to 100 with the series, yet the books never feel like a workbook. Parents don't need to explain everything; letting a child look, narrate and imagine life in each home is often the best part of the reading.

With younger children

With children of about 2–3, there is no need to aim for counting to 100. Readers describe little ones enjoying pointing at creatures, naming objects, guessing who lives next and climbing the stairs with a finger. Read a few groups of floors at a time, linger in a favourite home, and let counting come later, once the child is curious about the numbers.

Which book to start with?

Reader comments suggest most families start with the first book, 100かいだてのいえ, and branch out from there; it shows most clearly how the series works, and it is NIPIKO Books's suggestion if you're unsure.

Each book stands alone, though, so starting from whatever world your child already loves makes good sense: ちか for bug and digging fans, うみ for sea lovers, ぬま for young naturalists. NIPIKO Books does not rank a “best” book — the six differ in setting and residents, not in quality.

Reading-together ideas

• Before turning to the next ten floors, ask: “Who do you think lives up next?”
• Pick one thing to hunt for on every floor — a chair, a meal, a bed — and change it each time you read.
• Afterwards, draw your own many-storey house on a long strip of paper, with residents your child invents.

Mini, large-format and other editions

Besides the six main books, 偕成社 publishes small board-book editions (ミニ), large-format ビッグブック editions and gift boxes. These are other editions of the same works with their own ISBNs, so check the ISBN when buying. The mini editions are much smaller, which matters for such detailed pictures. Merchandise and the publisher's printable activities are not counted as titles.

• ボードブック100かいだてのいえミニ · ISBN 9784033327105 — Small 13 × 18 cm board-book edition (2015), separate from the main book.
• ボードブックちか100かいだてのいえミニ · ISBN 9784033327204 — Small board-book edition (2015).
• ボードブックうみの100かいだてのいえミニ · ISBN 9784033327303 — Small board-book edition (2015).
• ボードブックそらの100かいだてのいえミニ · ISBN 9784033327402 — Small board-book edition.
• ボードブックもりの100かいだてのいえミニ · ISBN 9784033502205 — Small board-book edition.
• ぬまの100かいだてのいえミニ · ISBN 9784033503400 — Small edition (2024).
• ビッグブック100かいだてのいえ · ISBN 9784033317403 — Large-format edition for group read-alouds (2009); each of the six main books has its own ビッグブック.
• ギフトボックス100かいだてのいえ（全６巻） · ISBN 9784033502915 — Gift box of the six main books (2024); same contents as the individual books.
• すうじかるた 100かいだてのいえ · ISBN 9784033328003 — A number karuta card game (2016) — a companion product, not a picture book.