Tomoe River Paper: 52 gsm, Sanzen & Fountain Pens

Drawing of a 100-sheet pack of Tomoe River S 52 gsm A5 paper, 148 mm wide, beside a sheet written in black ink with faint writing from its back showing through; inset: 52 g/m², shows through — An A5 pack of 100 loose sheets and one written sheet, drawn to scale; the packaging is simplified.

Product facts

Product: Tomoe River S 52 gsm Loose-Leaf Paper, A5, Blank, White, 100 sheets (Sanzen)
Brand: Tomoe River
Brand origin: Japan
Made in: Japan^*
Material: 52 g/m² Tomoe River S paper, blank, white
Released: February 2022^*
Price range: $$$5–20 per ream or pad

Notes on these facts

Made by Sanzen Paper Co., Ltd. (三善製紙, Kanazawa, Ishikawa). Made in Japan: Papeterie Makkura lists this A5 white pack (EAN 4909171851502) as made in Japan, and Pulp Addiction says the same for the A5 and A4 sheets. Yamamoto Paper's Japanese wholesale listing says Sanzen (三善製紙) makes the paper in Kanazawa, Ishikawa, and gives 生産地 (place of production) Japan for its Tomoe River S pad. We found no official Sanzen website. Source. Price: example listing. Released: Yamamoto Paper's Japanese listing says Sanzen began full-scale production of Tomoe River S in February 2022; the original Tomoegawa paper ended in 2021.
Price bands are typical US retail, checked October 2026.

Key takeaways

Tomoe River S loose-leaf paper is 52 gsm; one A5 pack holds 100 blank sheets of 148 × 210 mm (5.8 × 8.3 in).
At 52 gsm it is about 35% lighter than the 80 gsm paper in a Rhodia pad or a Leuchtturm1917 notebook.
Tomoegawa, founded in 1914 in what is now Shimizu, Shizuoka, ended production in 2021; Sanzen began full production of Tomoe River S in February 2022.
Yamamoto Paper says the Sanzen paper is about 5 microns thicker and stiffer; a 2022 review found it toothier but still free of feathering and bleed-through.
Retailers list the Sanzen sheets, pads and notebooks as made in Japan, in white or cream (ivory).

What is Tomoe River paper?

Tomoe River is a very thin, lightweight Japanese writing paper known for handling fountain pen ink well. It is sold as loose sheets, notepads and notebooks, and it is the paper inside the Hobonichi Techo.

Its reputation comes from fountain pen users. Galen Leather calls it the number one fountain pen paper, and JetPens gives Tomoe River its own category of loose sheets, pads and notebooks.

Who makes Tomoe River paper now?

Sanzen Paper (三善製紙) of Kanazawa, Ishikawa, makes it; the original maker, Tomoegawa, no longer does. Tomoegawa’s own history says the company (巴川製紙所, literally “Tomoe River paper mill”) was founded in 1914 in what is now Shimizu-ku, Shizuoka.

Yamamoto Paper, a Japanese paper seller, says Tomoegawa ended production in 2021 after a change in business policy and passed the brand to Sanzen, which has made 52 g/m² planner paper since 1976. Sanzen began full-scale production of Tomoe River S in February 2022, and The Gentleman Stationer reported in May 2022 that Sanzen had bought the formula and naming rights. Retailers now sell it as Sanzen Tomoe River, Tomoe River FP or Tomoe River S.

Tomoe River S loose-leaf paper specs

Spec	A5 pack (this guide)
Name	Tomoe River S 52 gsm Loose-Leaf Paper (also sold as Tomoe River FP)
Maker	Sanzen Paper Co., Ltd.
Weight	52 gsm
Sheet size	148 × 210 mm (5.8 × 8.3 in), A5
Sheets	100, loose
Ruling	Blank
Color	White (also sold in cream)
JAN (white A5)	4909171851502 (cream: 4909171851557)
Item code	SR-A5P-W (cream SR-A5P-C)
Made in	Japan

Size, count, JAN and origin come from Papeterie Makkura; the item codes from The Journal Shop. No source we found gives a sheet thickness in millimeters, but Yamamoto Paper says the Sanzen sheet is about 5 microns thicker than the original.

How thin is 52 gsm?

52 gsm is about two thirds of the 80 gsm used in most quality notebooks, which makes Tomoe River among the lightest writing papers sold by the sheet. It is also lighter than 20 lb (75 gsm) Hammermill copy paper.

Bar chart of paper weights to scale: Tomoe River S 52 g/m², Hammermill Copy Plus 75, Rhodia No. 16 80, Leuchtturm1917 80 and Midori MD Paper about 80 g/m² — Tomoe River weighs about 35% less than an 80 gsm notebook page.

Thin paper has two practical effects. More sheets fit in a slim notebook, and writing shows through from the other side. Galen Leather says the sheet is coated on both sides so ghosting is minimal, and that feathering generally isn’t a problem; bleed-through, where ink passes right through, is rarer than show-through.

How does Tomoe River paper handle fountain pen ink?

Retailers and reviewers say it resists feathering and bleed-through, and that ink sits on the surface. Galen Leather says pools of color stay on top of the sheet, which suits inks that show shading and sheen. Mountain of Ink, for example, saw the faint green sheen of Diamine Oxblood only on large swabs on Tomoe River.

Ink that sits on the surface usually takes longer to dry, but no source we found gives a drying time, and we haven’t timed it yet. The Gentleman Stationer found the Sanzen version stiffer and with more tooth than the original Tomoegawa paper, with darker ink and less shading and sheen, and said it still met the main promise: lightweight paper that takes fountain pen ink without feathering or bleeding.

Yamamoto Paper explains why: Sanzen reworked the mix of eucalyptus and softwood pulp, which made the fibers more uniform, the surface smoother and the paper firmer. It also says the sheet no longer cockles when you rub out FriXion ink, and that in its own tests even low-viscosity J. Herbin inks dried quickly without bleeding through.

What sizes and formats can you buy?

The loose sheets come in A5 and A4 packs of 100; the same paper is sold in notepads and A5 notebooks.

Format	Size	Count
Loose sheets	A5, 148 × 210 mm	100 sheets
Loose sheets	A4, 210 × 297 mm	100 sheets
Notepad	A5 or A4	100 sheets
Softcover notebook	A5	64 or 160 pages
Hardcover notebook	A5	368 pages

Formats come from Pulp Addiction and Papeterie Makkura listings. Rulings vary: Makkura also lists dot grid and grid notebooks.

How does it compare to other fountain pen papers?

Tomoe River is the thinnest of the well-known fountain pen papers; MD Paper and Rhodia are heavier and show less through.

	Tomoe River S	Midori MD Paper Pad	Rhodia No. 16
Weight	52 gsm	About 80 gsm	80 gsm
Color	White or cream	Cream	White
Format	Loose sheets, pads, notebooks	Glued pad	Stapled top pad
Made in	Japan	Japan	France

For a full comparison of notebooks, see our guide to the best notebooks for fountain pens.

Where is Tomoe River paper made?

In Japan: Sanzen makes the paper in Kanazawa, Ishikawa Prefecture, according to Yamamoto Paper. Papeterie Makkura gives the origin as Japan on its Sanzen listings, and Pulp Addiction lists the A5 and A4 sheets the same way. We found no official Sanzen website to confirm the mill.

Frequently asked questions

Who makes Tomoe River paper now?

Sanzen Paper (三善製紙) of Kanazawa, Japan, which Yamamoto Paper says has made 52 g/m² planner paper since 1976. The original maker, Tomoegawa, ended production in 2021, and Sanzen bought the formula and naming rights and began full production in February 2022.

What is the difference between Tomoe River S and Tomoe River FP?

They are names for the same Sanzen paper. Yamamoto Paper in Japan calls it 三善トモエリバーS (Sanzen Tomoe River S), while European retailers such as Papeterie Makkura list the same loose sheets as Tomoe River FP, for fountain pen.

Is the new Sanzen Tomoe River paper the same as the old one?

Not exactly. Yamamoto Paper says Sanzen redesigned the pulp mix, making the paper about 5 microns thicker and stiffer. The Gentleman Stationer's 2022 review found it toothier, with darker ink and less sheen, though it still handled fountain pen ink without feathering or bleeding.

Does Tomoe River paper show through?

Yes. At 52 gsm the sheets are thin, so writing shows from the other side, though Galen Leather calls the ghosting minimal and The Gentleman Stationer found less of it on the Sanzen paper. Ink bleeding right through the sheet is a separate, rarer problem.

What sizes does Tomoe River paper come in?

Sanzen's loose sheets come in A5 (148 × 210 mm) and A4 (210 × 297 mm), 100 sheets per pack. The same paper is sold in A5 and A4 notepads and in A5 notebooks of 64, 160 and 368 pages.

Is Tomoe River paper white or cream?

Both. Sanzen sells white and cream versions; Papeterie Makkura describes the cream A5 sheets as ivory.

Why do fountain pen users like Tomoe River paper?

Galen Leather says pools of ink sit on the surface, which shows off shading and sheen, and retailers say it resists feathering and bleed-through despite being thin. It also packs many pages into a slim notebook, which is why the Hobonichi Techo uses it.

Sources (13)

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