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Japanese fabric sourcing
Every piece starts with fabric sourced from mills in Nishiwaki and Kiryu. We visit in person twice a year and select runs by hand.
Refined swimwear and lingerie, made in Japan
Summer Noir. Our new resort collection.
Structured bikinis and soft-cup bralettes in Japanese Omi linen and Italian stretch lace. Cut for the body, not the mannequin.
Current collection
04 pours
01
Omi Linen Bandeau Bikini
¥28,000
Top and bottom in Omi linen sourced from a small weaver in Shiga Prefecture. The bandeau …
02
Nude Series Bralette
¥14,500
Cut from the double-knit stretch cotton from Nishiwaki Textile that started the whole lin…
03
Kiryu Silk Slip
¥32,000
Bias-cut from a habotai silk produced at a family-run mill in Kiryu, Gunma. The weight is…
04
Structured Triangle Bikini
¥24,000
The triangle top is lined with a thin layer of Japanese mesh to hold its shape in water. … Hours
Contact us
Sat 12:00-17:00 (showroom, by appointment); online orders accepted 24/7
Our address
The roastery
Standing order
Our products
Refined swimwear and lingerie, made in Shimokitazawa since 2018.
Our story
We argued about cup seam placement until we got it right.
Nex Core Flow Path started in a rented room in Shimokitazawa in the autumn of 2018. Yuki Tanaka had spent four years as a pattern-cutter at a mid-size lingerie manufacturer in Osaka, and left after growing tired of watching beautiful fabric get cut into shapes that fit no one particularly well. The first collection was six pieces, made on a single Juki industrial machine, sold through a small Instagram account to friends and friends of friends. The first run sold out in eleven days. Yuki took that as a signal.
The turning point came in spring 2020, when a fabric buyer at Nishiwaki Textile introduced Yuki to a small mill producing a double-knit stretch cotton with a weight and hand-feel unlike anything available from the usual wholesale suppliers. That fabric became the foundation of the Nude Series, which remains the most requested line in the collection. Around the same time, Yuki hired Hana Mori, a former swimwear designer from a Kyoto resort brand, to lead the swimwear side of the business. The two of them spent that summer cutting and re-cutting bikini patterns on a dress form in Yuki's living room, arguing about cup seam placement until they got it right.
Our story
- 01 Select your fabric and colourway from the current run
- 02 Complete the fit questionnaire at checkout
- 03 Allow ten to fourteen days for custom sizing
- 04 Receive your piece, hand-packed in washi tissue
Coffee subscription
Refined swimwear and lingerie, made in Shimokitazawa since 2018.
News & Announcements
News & Announcements
2026-06-10
How to find a bikini top that actually fits a fuller cup
Most swimwear is designed around a B or C cup sample size. The pattern is graded up from there, which means a size 14 top in a D cup is often just a scaled-up B cup pattern, not a redesigned one. The result is cups that gap at the top, straps that pull forward, and underwires that sit on breast tissue instead of below it. If this sounds familiar, the problem is the pattern, not your body.
Read more →2026-05-28
Why we use Omi linen for swimwear and how it holds up
Linen swimwear sounds counterintuitive. Linen is a natural fibre, it absorbs water, and it wrinkles. All of that is true. It's also fast-drying, naturally UV-resistant, and gets softer with every wash without losing its structure. For a swimsuit worn at a beach lunch or a resort pool, not in competitive laps, linen is a genuinely good choice.
Read more →2026-04-15
Kiryu silk: the Japanese textile tradition behind our slips
Kiryu is a small city in Gunma Prefecture, about two hours north of Tokyo by train. It's been a silk-weaving centre since at least the eighth century, when the region's climate and access to mulberry trees made it a natural home for sericulture. At its peak in the Meiji era, Kiryu was producing silk for export across Europe and North America. Most of that industry is gone now. A handful of family mills remain.
Read more →Our products
What sets us apart
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Made-to-order sizing
We offer eight cup sizes and five band widths. If the standard size chart doesn't fit, we adjust the pattern at no extra charge.
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Small-batch production
Each style is produced in runs of thirty to fifty pieces. When a run sells out, it's retired. We don't restock indefinitely.
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Ethical Tokyo atelier
All sewing is done in our Shimokitazawa atelier by four full-time seamstresses. No offshore production, no subcontracting.
Founder
Meet the maker
Founder, Established since 2018
Yuki Tanaka
Yuki Tanaka trained as a pattern-cutter at Maison Sato, a mid-size lingerie manufacturer in Osaka, where she spent four years learning to grade swimwear and bralette patterns before realising the industry's standard sizing was built around a single sample size. She left in 2017, spent a year freelancing for a small Tokyo boutique called Hare, and founded Nex Core Flow Path in Shimokitazawa in autumn 2018. Outside the studio, she rides a Miyata touring bicycle along the Tama River on Sunday mornings and keeps a small collection of 1970s Japanese jazz records. She cups every new fabric sample herself before it goes anywhere near a cutting table.
Reviewed by clientsGDPR compliantEco-conscious