The PFU HHKB Professional Series Keycap Set in Sumi (black) with top-left legends, model PD-KB400KTB, is a genuine replacement part for English-layout HHKB keyboards. This article covers how to confirm compatibility, what the swap actually involves, and how this set differs from the blank and center-printed variants.
Overview
PD-KB400KTB is a genuine 60-piece keycap set for English-layout HHKB Professional keyboards. The color is Sumi (black) and the legends are printed in the top-left corner, matching HHKB's standard printing style.
A keycap puller and an instruction manual are included, so you can do the swap yourself the day it arrives.
The short version: this set is for people who want their existing HHKB to look and read like it did on day one. If you want to change how the board feels, or you are shopping for shine-through or novelty caps, look elsewhere.
The caps are stated to be identical in material and shape to the factory ones, so typing feel stays the same. For a repair part, "nothing changes" is exactly the point.
Amazon.co.jp shows 32 reviews averaging 4.7 out of 5 (94% positive, captured 2026-06-02).
That is a strong score, but the sample is small — read it as "no widespread complaints about this part" rather than as a statistically solid rating.
Compatibility Guide
The set fits these seven models, English (US) layout versions only:
- HHKB Professional
- HHKB Professional2
- HHKB Professional2 Type-S
- HHKB Professional BT
- HHKB Professional HYBRID Type-S
- HHKB Professional HYBRID
- HHKB Professional Classic
Three things to verify before ordering.
Layout. The English layout has 60 keys; the Japanese layout has 69 and a different arrangement.
This set will not fit a Japanese-layout HHKB — those need the PD-KB420 series instead. If you are unsure which you own, look for extra keys flanking the space bar, which indicates the Japanese layout.
Stem shape. HHKB Professional boards use electrostatic capacitive (Topre-style) switches, whose keycap mounts differ from the usual Cherry MX cross stem.
Off-the-shelf MX keycap sets will not fit an HHKB Professional, and PD-KB400KTB cannot be reused on a typical mechanical keyboard. Assuming "keycaps are a standard" is the single most common misunderstanding around this product.
Series and generation. Only Professional-series boards are listed.
Models outside that list — including later series and derivatives built on different switch mechanisms — are not covered. Check the model number on the underside of your keyboard against the list, character for character, and consult the manufacturer's compatibility page if anything is ambiguous.
How to Swap the Keycaps
The job needs one tool and no disassembly, but a few habits prevent mistakes.
- Photograph the layout first. Remembering where all 60 caps went is harder than it sounds.
One overhead phone photo solves it. 2.
Pull straight up. Hook the puller on opposite corners and lift vertically.
Angling the tool stresses the cap and the housing. 3.
Save the wide keys for last. The space bar tilts easily, so lift it a little at a time from both sides.
Clean while it is open. A fully stripped board is the best chance you will get to blow out dust with compressed air or a soft brush.
Seat each cap fully. Press straight down until it clicks; a half-seated cap feels notchy when typed on.
Budget roughly 30 minutes including cleaning. No soldering, no special tools.
Choosing Between the Keycap Sets
PFU offers several sets in this family, and you choose along three axes: layout, legend position, and color. PD-KB400KTB is the English / top-left printed / Sumi combination.
| Axis | Options | How to decide |
|---|---|---|
| Layout | English (PD-KB400 series) / Japanese (PD-KB420 series) | Dictated by your keyboard; no real choice |
| Legend | Top-left printed / center printed / blank | Looks, plus whether you glance at the keys |
| Color | Sumi, white, Fuji, and others | Match the case, or deliberately contrast it |
One warning matters most here. PD-KB400KTB is a printed set, so buying it will not give you a blank board for touch-typing practice. For that you need a blank (mukokuin) set.
Conversely, if you run a blank HHKB and have decided you want legends back, this is exactly the fix.
Mixing colors is also fair game: Sumi caps on a white case, or the reverse, is physically fine and is one of the perks of a genuine lineup that ships in multiple colors.
Product Info
| Item | Value |
|---|---|
| Keycap count | 60 |
| Supported layout | English (QWERTY) |
| Legend | Top-left printed |
| Color | Sumi (black) |
| Included | Keycap puller, instruction manual |
| Package size | 37.3 × 16.1 × 5.6 cm |
The count of 60 matches the key count of an English-layout HHKB, so one set covers an entire board. The 37 cm-wide box reflects the caps being laid out and fixed on a tray, which is worth knowing if you were expecting something mailbox-sized.
On pricing: ￥6,600 on Amazon.co.jp as captured on 2026-06-02 (ASIN B00FPH4K5O), versus ¥9,570 on Rakuten (Seikatsu Ryohinkan) as captured on 2026-08-17.
The Rakuten figure is a marketplace listing, which tends to drift upward when stock is tight. Both are point-in-time captures and will move with sales, stock, and exchange rates — always check the live product page before buying.
Reviews stand at 32 with a 4.7 average (94% positive, captured 2026-06-02). Fine for a spare part, but a small sample.
In market terms this is clearly pricier than third-party keycap sets. Given the capacitive stem, however, the field of options that actually fit is narrow — you are paying for a guaranteed fit, and that framing makes the price easier to accept.
Best Use Cases
- Long-time HHKB owners with shiny or faded caps. Genuine parts restore the look without altering the feel of a board you already know.
- Blank-keycap owners who want legends back. Blank boards look great but leave you hunting for symbol and modifier keys; top-left legends are a good balance of legibility and clean looks.
- Buyers of second-hand HHKBs. A full cap swap resolves hygiene worries and cosmetic wear at once, especially paired with a cleaning session.
- Anyone building a two-tone board. Sumi caps on a lighter case is an easy, reversible customization.
- People who want spares on hand in case a single cap breaks later.
Things to Check Before Buying
This is where the set is a poor fit.
It will not change how your board feels. The caps match the factory spec, so typing feel is unchanged.
To alter feel, look at silencing rings or dome changes instead.
It is the wrong set for touch-typing practice. PD-KB400KTB has legends.
Choose a blank set if you want an unmarked board. Overlooking the "top-left printed" part of the product name is a common and avoidable mistake.
It does not fit Japanese-layout HHKBs. Different key count, different arrangement.
Return policies vary by retailer, so checking first is the only real protection.
It does not fit other mechanical keyboards. The capacitive stem is not Cherry MX compatible.
Watch both the price gap and the listing details. The same item was ￥6,600 on Amazon in June 2026 and ¥9,570 on Rakuten in August 2026.
Listing metadata — seller, fulfiller, color and layout wording — can also disagree with the actual item on shopping pages generally. Cross-check the three attributes in the product name (English layout, top-left legends, Sumi) against the product photos before ordering, and if the page lets you switch between color or legend variants, confirm which variant is selected right before you confirm the order.
Treat it as a consumable. Warranty handling follows the manufacturer's and retailer's policies for accessories; this is not a long-warranty purchase.
FAQ
Q. Does the swap require soldering or disassembly? A.
No. Pull the old caps with the included tool and press the new ones on.
About 30 minutes including cleaning.
Q. Will typing feel change?
A. Essentially no — the caps are stated to match the factory material and shape.
Q. Do 60 caps cover the whole board?
A. Yes. That matches the English-layout HHKB key count, so one set replaces everything.
Q. Will it fit a Japanese-layout HHKB?
A. No. Use the PD-KB420 series for that layout.
Q. Can I substitute a generic keycap set? A.
Generally not. HHKB Professional uses capacitive switches with a different stem from Cherry MX caps.
Q. Can I replace only some keys? A.
Yes. Wear concentrates on the home row, Enter, and the space bar, so swapping those and keeping the rest as spares is a valid approach.
Product Disclosure (Amazon)
- Manufacturer: HHKB
- Seller: PFUダイレクト
- Fulfilled by: PFUダイレクト
- ASIN: B00FPH4K5O
- Note: This article covers a manufacturer-made product based on Amazon listing details.
