Compiled from 7 sources; we haven't tested this product ourselves yet. How we research
Quick answer
The isshoni. insert notebook from Daigo of Osaka is a slim 48-page notebook with a polypropylene cover, made a little smaller than standard A5 or B6 so it slides into a notebook cover or planner pocket. Retailers list it in A6, B6 and A5, about 4 mm thick, with a 5 mm grid.
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Notes on these facts
Made by Daigo Corporation (Osaka). Made in Japan: Maruzen Junkudo, bungu.store and The Journal Shop give Japan; Daigo's isshoni. page doesn't state it. Source. Price: example listing.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43 = CZK 21.7; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).
Key takeaways
Maruzen Junkudo lists the A6 at 146 × 100 × 4 mm and 35 g, the B6 at 180 × 124 × 4 mm and 54 g, and the A5 at 208 × 144 × 4 mm and 72 g, all with 48 pages.
Daigo says it made the notebooks smaller than exact B6 and A5 on purpose, so they slide into notebook covers and planner sleeve pockets.
Daigo's page lists B6 and A5 only, in clear or black and in grid or ruled; Maruzen Junkudo, bungu.store and The Journal Shop list grid only, in white or black, and add an A6.
Daigo lists the B6 at ¥308 (about US$1.90) and the A5 at ¥352 (about US$2.20) with tax; The Journal Shop priced the A5 at £5.50 (about US$7.30).
The 5 mm grid has a composition line, a margin for headings, per Daigo, bungu.store and The Journal Shop; only Maruzen gives the 48-page count.
What is the isshoni. insert notebook?
It is a thin extra notebook that rides inside a cover or planner next to your main book. Daigo of Osaka makes it for its isshoni. line for office workers, which our DAIGO story covers. Daigo says it is for adding pages when the notebook in your cover is short on room.
Its page calls it a thin notebook with a hard polypropylene cover. The shops call it the Insert Notebook or the Slim Grid Notebook.
What are its specs?
Three sizes, each about 4 mm thick with 48 pages. The sizes and weights are Maruzen Junkudo’s white grid listings; bungu.store and The Journal Shop give the same sizes. Prices are Daigo’s tax-included list prices where its page lists the size.
Size
Body (H × W × D)
Weight
Daigo price
A6
146 × 100 × 4 mm (5.7 × 3.9 × 0.2 in)
35 g
Not on Daigo’s page
B6
180 × 124 × 4 mm (7.1 × 4.9 × 0.2 in)
54 g
¥308 (about US$1.90)
A5
208 × 144 × 4 mm (8.2 × 5.7 × 0.2 in)
72 g
¥352 (about US$2.20)
The Journal Shop gives 200 g for the whole range. We read that as a shipping weight, since Maruzen’s 72 g for the A5 is far lower.
Why is it smaller than standard size?
Daigo says it designed the notebooks slightly under exact B6 and A5 size so they slip into covers and sleeve pockets. The A5 is 208 × 144 mm against the standard 210 × 148 mm, and the B6 is 180 × 124 mm against 182 × 128 mm. Our drawing shows the difference, and how much thinner it is than a Notebook Number.
A 5 mm grid with a composition line, a margin line for headings. Daigo says the grid is easy to use and lists the composition line, and bungu.store and The Journal Shop say the same. Daigo’s page also lists a ruled version with 6 mm lines and 6 mm gaps, and thick lines that split a page into three.
We found the ruled version only on Daigo’s page, for B6 and A5.
What cover colors and finish does it have?
Daigo says clear or black; three shops say white or black. Daigo’s clear cover is for decorating, it says, and its black suits business. bungu.store and The Journal Shop add a gold foil stamp.
Daigo’s page doesn’t mention foil for this notebook. We can’t tell whether the white is the clear cover renamed or a newer build.
Which size should you choose?
In our view, match it to your cover. Use the A5 insert in an A5 cover and the B6 in a B6 one. The A6 only appears at three retailers, so check availability.
In Japan, per Maruzen Junkudo, bungu.store and The Journal Shop. Daigo’s page doesn’t say.
We found no US-dollar listing, so our $$ band ($5–20) rests on shops abroad and imports.
The Journal Shop priced the A6 at £4.50 (about US$5.90), the B6 at £5.00 (about US$6.60) and the A5 at £5.50 (about US$7.30). Maruzen listed ¥440 (about US$2.80), ¥495 (about US$3.10) and ¥550 (about US$3.50), and bungu.store ¥900 (about US$5.70), ¥1,000 (about US$6.30) and ¥1,100 (about US$7.00).
Daigo’s own prices are the lowest we found. For another low-priced Japanese notebook with a function for each book, see the Luddite Function Notebook.
Frequently asked questions
Why is the insert notebook smaller than a normal A5?
Daigo says the size is designed a little under exact B6 and A5 so the notebook slides easily into notebook covers and planner sleeve pockets. The A5 is 208 × 144 mm against the standard 210 × 148 mm.
How many pages does it have?
48 pages, per Maruzen Junkudo. Daigo's page and the other shops we checked don't give a count.
Is it a grid or a ruled notebook?
Both exist on Daigo's page. The shops we checked list only the 5 mm grid, which has a composition line for headings.
Is the cover white or clear?
Daigo's page says clear or black. Maruzen Junkudo, bungu.store and The Journal Shop say white or black, so the sources differ; we can't tell if white is a renamed clear.
Does it have a gold foil cover?
bungu.store and The Journal Shop say the cover is stamped with gold foil. Daigo's page for this notebook doesn't mention foil.
Will it fit the isshoni. pen case cover?
The A5 insert is 208 × 144 × 4 mm and Jenni Bick says the A5 PVC cover takes notebooks up to about 12 mm thick, so it should fit. We haven't tried it.
Is it the same as the Notebook Number?
No. The Number has 192 numbered pages and a front index and is about 11 mm thick; the insert has 48 grid pages and no page numbers.
