Rectal bleeding or pain after a prostate device? | The diary records injuries and design changes [OK Prostate Chip]

This page is based on entries from "ok-lab's diary" (https://ok-lab.hatenablog.com/), the Japanese development diary written by Mr. Okada, founder of OK Lab, a small company in Japan (Okada Comfortable Life Laboratory). Only the entries about "rectal bleeding and bowel-wall problems" are summarized here, in order of publication. Past prices and sizes are as written at the time. Current prices come from the official product list (retrieved September 4, 2026). Quotations are translated from Japanese.

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Note: This page is a personal reading log by someone with no connection to the maker or the seller. It reflects the source entries as of their publication dates and makes no guarantee of accuracy or safety. The product is not a medical device; talk to a doctor about any health decision. Check the official site for current information. This page contains advertising.

In short

• The diary records rectal bleeding, pain, damaged prototypes, and a covered chip moving entirely inside.
• Mr. Okada changed designs and later attributed earlier unexplained bleeding to a tiny exposed wire projection.
• The current product list includes the urethral products ordered by a reader asking about combined anal stimulation.

If you see blood in your urine, even a small amount or for the first time, do not wait and see. See a urologist right away. If you suddenly cannot urinate, or the device cannot be removed, do not try to fix it yourself. Go to a medical facility, including emergency care, immediately.

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About this product

The OK Prostate Chip is a small device that is placed in the urethra (the urine passage) so that it acts on the prostate; the maker sells it in several shapes, sizes and materials. It is made and sold by OK Lab (Okada Comfortable Life Laboratory), a small company in Japan, through its own online store, and prices are in Japanese yen (JPY).

The maker's development diary, "ok-lab's diary", is written in Japanese. This page is an English summary of it, and every quotation is translated. OK Lab ships internationally, so readers outside Japan can order (see "Buying from outside Japan" below).

Product names on this page are plain-English descriptions. The official Japanese product name is shown once in the product table so you can find the same item in the store.

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Before you read: key terms

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What happens: rectal bleeding after use

The OK Prostate Chip is a small device placed in the urethra (the urine passage) to act on the prostate. Rectal chips are separate devices intended to stimulate the prostate from the bowel side, through the anus. These entries describe blood on devices or stool, discomfort, damaged materials, and chips moving farther inside. Mr. Okada describes designs intended to change pressure and reduce unwanted contact with the bowel wall.

Rectal bleeding concerns led Mr. Okada to withdraw the twist prototype

In an entry published in September 2018, Mr. Okada withdrew the rectal twist prototype from sale. He said his own tendency to bleed had limited earlier testing. He planned a revised rectal massager that he hoped would suit people prone to anal tears. Mr. Okada asked readers to wait until the new proposal was ready.

(Source: ok-lab's diary, published September 2018)
https://ok-lab.hatenablog.com/entry/20180901/1535779541

Blood on stool stopped the planned rectal chip launch

In an entry published in October 2018, Mr. Okada reported blood on a rectal chip and dark blood on stool. Bleeding followed forced, dry removal after more than 12 hours; it recurred after use the following day. An anoscopy (an examination of the anus) found no abnormality or visible bleeding, according to his account.

He reported that the doctor mentioned his blood-thinning medicine and cases of bowel injuries involving devices. Mr. Okada postponed commercialization indefinitely while the cause remained unresolved. He told readers awaiting a release that sales could not proceed until his bleeding had been explained.

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181013/1539409481

Damaged resin raised concerns about exposed wire and rectal bleeding

In an entry published in October 2018, Mr. Okada described damage to resin (the material surrounding the internal wire). It dissolved after about 5 days in bleach diluted 20-fold. He considered this a possible explanation for wire becoming exposed on a test chip. Mr. Okada warned that the previously suggested bleach treatment could damage the resin.

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181020/1540018080

Rectal chip snagging concerns prompted a rounded loop design

In an entry published in November 2018, Mr. Okada announced sales of a rounded loop design intended to address snagging concerns. Published specifications were about 11cm long, 3cm, 4cm, or 5cm wide, and 3cm deep. The 4cm version cost ¥7,000 (about $45 at ¥156 = $1, rate as of 2026-09-04) excluding tax, as published in November 2018.

Custom pricing added ¥350 (about $2 at ¥156 = $1, rate as of 2026-09-04) for each 1cm of additional resin sheet. Mr. Okada directed requests beyond those published specifications to custom orders.

(Source: ok-lab's diary, published November 2018)
https://ok-lab.hatenablog.com/entry/20181123/1542963370

Anal pain accompanied belt rubbing before a covered chip moved inward

In an entry published in November 2018, a customer described a covered spiral chip and its control belt. The belt rubbed painfully near the anus and was removed after 5 hours. At around 12 hours, the covered chip had moved entirely inside.

The customer reported eventual removal without bleeding or deformation. Mr. Okada attributed the movement to the covering's attachment position and referred the customer to his attachment guidance.

(Source: ok-lab's diary, published November 2018)
https://ok-lab.hatenablog.com/entry/20181123/1542963370

Earlier rectal bleeding was later attributed to a tiny wire projection

In an entry published in September 2021, Mr. Okada revisited his earlier unexplained rectal bleeding. He concluded that a tiny exposed wire projection had caused it, despite being undetectable by fingertip touch. A newer bleeding incident involving a thin resin-covered wire device brought that earlier problem back to mind. Mr. Okada withheld that newer wire design from sale until he could establish its safety.

(Source: ok-lab's diary, published September 2021)
https://ok-lab.hatenablog.com/entry/2021/09/11/125735

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The maker's answer to rectal bleeding after use

Mr. Okada proposed changes to tips, coverings, and seals, and advised against prolonged rectal use of a vibrating chip.

A customer's rectal bleeding concern changed the proposed tip

In an entry published in October 2018, a customer requested a rounded tip on a spiral prototype to reduce feared scratching. Mr. Okada said he had previously considered that unnecessary, but his own bleeding changed his response. He accepted the request; an entry later that month described enlarged, rounded tips as his proposed precaution against bowel-wall injury.

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181013/1539409481

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181020/1540018080

A covering felt gentler during the maker's rectal chip tests

In an entry published in October 2018, Mr. Okada changed his proposal to include a condom covering (a barrier around the chip). He reported gentler contact with the bowel wall and muscles around the anus. A separate proposal added water within the covering, intended to cushion movement. He warned that a 10cm spiral could risk rupture and might need a stronger covering.

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181020/1540018080

Prolonged rectal chip use made vibration stressful after its position changed

In an entry published in August 2019, a customer had found a vibrating chip's motor area too large for urethral use. Mr. Okada returned an altered chip, but the diary does not record whether the alteration resolved that problem. He had suggested rectal use as a fallback, then reported a drawback from his own experience.

He wrote that stool could shift the chip's position during prolonged use, making vibration stressful. Mr. Okada advised against prolonged rectal use and proposed external support near the pubic area as another approach.

(Source: ok-lab's diary, published August 2019)
https://ok-lab.hatenablog.com/entry/2019/08/17/132641

An incomplete seal prompted another change to the rectal chip

In an entry published in September 2022, Mr. Okada described a flat rectal device intended to provide pressure throughout the day. Its aluminium plate had a silicone tube covering; the chip was about 12mm wide and 25mm thick. He said the basic shape and pressure mechanism needed no change. Mr. Okada's stated correction was stricter sealing, after finding the earlier seal incomplete.

(Source: ok-lab's diary, published September 2022)
https://ok-lab.hatenablog.com/entry/2022/09/17/123057

If you see blood in your urine, even a small amount or for the first time, do not wait and see. See a urologist right away. If you suddenly cannot urinate, or the device cannot be removed, do not try to fix it yourself. Go to a medical facility, including emergency care, immediately.

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How rectal bleeding after use changed over time

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OK Prostate Chip products related to rectal bleeding after use

The current list identifies urethral products ordered by the reader who asked about simultaneous anal stimulation.

Products that appear in these entries

(Source: ok-lab's diary, published February 2020)
https://ok-lab.hatenablog.com/entry/2020/02/29/155031

Products the diary mentioned as alternatives

The diary names no alternative.

Withdrawn rectal twist prototype: No matching product can be confirmed on the current list.

Oversized spiral prototype: No matching product can be confirmed on the current list.

Historical loop specifications: No matching product can be confirmed on the current list.

Silicone-covered aluminium build: No matching product can be confirmed on the current list.

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Common worries about rectal bleeding after use

The questions concern cracked spirals, snagging, and pressure applied while a urethral chip is present.

"Is a cracked spiral chip safe after rectal pain?"

In an entry published in October 2018, a customer reported pink discharge after testing a 90mm spiral on October 24, 2018. They stopped another attempt after dull pain near the sigmoid colon (the bowel area they believed the chip had reached). Mr. Okada initially attributed stretching to incomplete curing (resin hardening), which he said took over 1 month.

The customer then reported a crack across the resin 2.5cm from the tip, after effectively 1 use lasting minutes. Mr. Okada now considered large spirals impractical and tentatively proposed a 4cm maximum diameter, cured for over 1 month. His revised advice favored smaller designs and a water-cushioned approach.

(Source: ok-lab's diary, published October 2018)
https://ok-lab.hatenablog.com/entry/20181027/1540618195

"Could a different shape prevent rectal chip snagging?"

In an entry published in December 2018, a customer asked whether a closed-loop shape would reach farther than their two-bump U-turn chip. They reported little sensation and worried that snagging during removal could cause injury. The diary does not record whether this customer received a design that resolved those concerns. Mr. Okada asked for time to consider a suitable proposal.

(Source: ok-lab's diary, published December 2018)
https://ok-lab.hatenablog.com/entry/20181201/1543652709

"Does combining anal pressure with a urethral chip cause bleeding?"

In an entry published in February 2020, a customer prone to anal bleeding asked about anal pressure or vibration alongside a urethral chip. They had ordered the curved ceramic urethral chip, female-connector resin chip, and three-hole urethral stopper listed above. Mr. Okada said he had received both successful and unsuccessful reports of combined use.

The customer later reported bleeding, pain, and inability to urinate during use of a homemade device with anal stimulation. That follow-up did not establish an outcome with the ordered products. Mr. Okada's answer warned that people unable to limit their actions might be better avoiding combined use.

(Source: ok-lab's diary, published February 2020)
https://ok-lab.hatenablog.com/entry/2020/02/29/155031

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Buying from outside Japan

OK Lab ships internationally to countries covered by Japan Post's EMS courier service. Overseas orders are paid in advance by PayPal. Each order carries a ¥400 (about $3 at ¥156 = $1, rate as of 2026-09-04) handling fee, and EMS shipping is charged on top. These terms come from OK Lab's official sales-terms page (written here as plain text, not a link: ok-lab.net/docs/law), checked on September 7, 2026; confirm them on the official store before you order, because they can change.

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Summary of this article

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Source: ok-lab's diary (Okada Comfortable Life Laboratory). The original entries are in Japanese; quotations on this page are translated. Photos and videos are on the original entries.