Compiled from 5 sources; we haven't tested this product ourselves yet. How we research
Quick answer
The isshoni. Day Log from Daigo of Osaka is an undated three-month planner in B6 Slim, 180 × 110 × 10 mm, with 194 pages. It gives each of 92 days a two-page spread with a 0:00 to 23:00 timeline, and adds monthly plans, a habit tracker and a monthly review. Four season-colored covers close with one elastic band.
Polypropylene (PP) cover; paper; single-corner elastic band
Price range
$$$5–20 per notebook
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Notes on these facts
Made by Daigo Corporation (Osaka). Made in Japan: Maruzen Junkudo's listing gives Japan as the country of origin, and The Journal Shop and bungu.store say made in Japan; Daigo's own isshoni. page doesn't list the Day Log. Source. Price: example listing.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43 = CZK 21.7; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).
Key takeaways
Maruzen Junkudo lists the Day Log at 180 × 110 × 10 mm with 194 pages, a PP cover and 185 g; The Journal Shop gives 399 g, which we read as a shipping weight.
It covers about 92 days: each day is a two-page spread with a timeline from 0:00 to 23:00, so the 184 daily pages are most of the book.
Yoseka lists the page split as 6 monthly-planning pages, a 2-page overview of three months plus one ahead, 184 daily pages and a 2-page habit tracker.
Four covers follow the seasons: green for spring, blue for summer, red for autumn and gray for winter, codes R1826 to R1829.
Japan's list price is ¥1,540 (about US$9.70) with tax, and the US-facing shops we checked listed it within our $$ band ($5–20) on October 28, 2026.
What is the isshoni. Day Log?
It is an undated three-month planner and diary from Daigo of Osaka, in a slim B6 size. The Journal Shop calls it a manageable alternative to a full-year diary: you start when you are ready, not when the calendar says so.
It belongs to Daigo’s isshoni. line for office workers, which our DAIGO story covers. Each day gets a two-page spread, so the Day Log suits people who want to log what happened as well as plan it.
What are its specs?
180 × 110 × 10 mm, 194 pages and a PP cover, per Maruzen Junkudo. Daigo’s own isshoni. page doesn’t list the Day Log, but its June 2026 release gives the same size and page count.
Spec
Value
Size
180 × 110 × 10 mm (7.1 × 4.3 × 0.4 in), B6 Slim
Pages
194
Weight
185 g (6.5 oz) per Maruzen; 399 g per The Journal Shop
Cover
Polypropylene (PP), with a single elastic band at the lower right
Layout
Grid, per Maruzen’s title; the grid spacing isn’t stated
Dates
None (undated)
Colors
Green R1826, blue R1827, red R1828, gray R1829
JAN (green)
4902041418263
The two weights disagree. 399 g is probably a shipping weight with packaging, but the shops don’t say.
How are its 194 pages laid out?
Mostly day spreads: 184 of the 194 pages are the 92 days. Yoseka lists the split as 6 pages of monthly planning, a 2-page overview, 184 pages of daily planning and a 2-page habit tracker.
Daigo’s text, as Maruzen gives it, calls each day a “Today’s Plan” spread with a timeline from 0:00 to 23:00 for appointments, logs and to-dos. The overview spread shows about three months plus one month ahead, for long projects and plans that cross months. At the back, a habit tracker records goals and a monthly review page records good points and regrets, so you can see progress after three months.
What do the four covers mean?
They are the four seasons, so each three-month book can have its own color. Green is spring’s fresh leaves, blue is summer’s sea, red is autumn leaves and gray is a snowy winter day, per Maruzen and Yoseka.
Maruzen says the idea is to enjoy a different color every three months. Four books make a year.
Who is the Day Log for?
In our view, for people who like to see a day’s hours at a glance. The 0:00 to 23:00 timeline helps if your day is cut into meetings, and the habit tracker suits one goal at a time.
If you want a whole year in one book, see our planners roundup. To choose between formats, our guide to how to choose a planner explains weekly against daily layouts.
How many Day Logs make a year?
Four, if you fill every day: 4 × 92 = 368 days, a little over a year, by our arithmetic. The season colors nudge you to buy one per quarter. Because the book is undated, skipping days stretches each one.
Are there special designs?
Yes: Daigo’s June 15, 2026 release lists a Day Log with Furukawa Shiko artwork, in a seal, a dog, a panda and a cat. It keeps the B6 Slim size and 194 pages, adds stickers for decorating a planner, and lists at ¥1,925 (about US$12) with tax.
How much does it cost and where can you buy it?
Yoseka listed it at US$18.00 and The Journal Shop at £14.99 (about US$20) on October 28, 2026, in our $$ band ($5–20). Yoseka is in New York; The Journal Shop prices in pounds.
bungu.store, a Japan-based shop, listed it at ¥3,100 (about US$20). Maruzen Junkudo listed ¥1,540 (about US$9.70) with tax, so US-facing prices are roughly double. The Furukawa Shiko version, with stickers, lists at ¥1,925 (about US$12) with tax.
We found no listing at JetPens or Jenni Bick on that date.
Daigo also sells covers with a built-in pen case; our isshoni. PVC pen case notebook cover guide gives their closed sizes, so you can check whether a Day Log’s 180 × 110 mm body suits one.
Frequently asked questions
Is the isshoni. Day Log dated?
No. Yoseka and The Journal Shop both call it undated or date-free, so you start on any day and write the dates in yourself.
How long does one Day Log last?
About three months of daily use: it has 92 day spreads. If you skip days, a notebook lasts longer, since the days aren't tied to a calendar.
How many pages does the Day Log have?
194, which Maruzen Junkudo, The Journal Shop, Yoseka and bungu.store all list. Of those, 184 are the 92 two-page daily spreads.
Does it have a habit tracker?
Yes. A two-page habit tracker at the back lets you record goals and check them off each day, and a monthly review page lets you note what went well, per Maruzen's description of Daigo's text.
Is it a planner or a diary?
Both: Yoseka calls it a diary and The Journal Shop a planner. You write appointments and to-dos on the timeline and daily logs beside it, and with no printed dates it works as a diary you fill in as you go.
Does the Day Log have a pen loop?
None of the listings we read mention one. They describe a single elastic band anchored at one corner, which keeps the cover closed in a bag.
Does Daigo make a Day Log with sticker extras?
Yes. Daigo's June 15, 2026 release lists a Day Log in four Furukawa Shiko animal designs with bonus stickers for decorating, at ¥1,925 (about US$12) with tax.
