Fabric First
Every piece begins with the textile. We source Italian Lycra, French lace, and Japanese silk-blend jersey. Nothing enters the atelier unless it passes a hand-feel test first.
A nail salon like no other
Nails worth showing off.
Stream Lab Core Nex is a Tokyo-based boutique for women who know exactly what they want. Swimwear and lingerie cut from the finest fabrics, designed to be worn, not just admired.
Our products
Bone Coast Riviera Sand Blush Atelier Terracotta Dusk Calais Noir Pale Sage Champagne Lace Slate Côte
The carte
The Current Collection
Riviera Bikini Top
¥18,000
Cut from 78% ECONYL recycled nylon with an underwire channel and adjustable halter ties. The cup is structured with a t…
Riviera Bikini Bottom
¥14,000
High-cut brief in the same ECONYL fabric as the Riviera top, with a flat elastic waistband and a single hip tie on each…
Côte One-Piece
¥28,000
A scoop-back one-piece in Italian Lycra with a built-in shelf bra and a low-cut front. The fabric has a matte finish an…
Calais Bralette
¥16,000
Made from Calais lace sourced from a mill in northern France that has been weaving the same pattern since 1962. The ban…
Our products
Why Stream Lab Core Nex
Made in Small Runs
We produce in runs of 30 to 60 pieces per style. When a style sells out, it is gone. That is not a marketing trick. It is how we keep quality consistent and waste minimal.
Fit Across Real Bodies
Our sizing spans XS through 3XL, graded by a pattern-maker in Osaka who has spent 18 years fitting women's swimwear. Every cup size is cut separately, not scaled.
News & Announcements
News & Announcements
2026-06-01
How ECONYL Recycled Nylon Becomes a Swimsuit
If you have seen the word ECONYL on a swimwear label and wondered what it actually means, you are not alone. It is one of the more substantive sustainability claims in fashion. But it is also one of the more misunderstood. Here is what the process actually involves, and why the fabric performs the way it does.
Read more →2026-05-10
How to Care for French Calais Lace Lingerie
Calais lace has a reputation for being delicate, and that reputation is not entirely wrong. But most of the damage we see on returned pieces is not from wear. It is from washing. The lace itself is remarkably durable. The problem is usually heat, agitation, or the wrong detergent. Here is what actually works.
Read more →2026-04-15
How to Find the Right Bikini Cup Size for Your Body
Swimwear sizing is genuinely confusing, and it is not your fault if you have never found a bikini top that fits properly. The problem is structural: most swimwear brands size cups from a single block and scale up or down, which means the cup shape changes with the size. Here is how to measure correctly and what to look for in a brand that sizes properly.
Read more →Quick quiz
Find Your Stream Lab Core Nex Piece
Answer four short questions and we will point you toward the styles most likely to work for your body, your plans, and your wardrobe.
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Founder & maker
Meet the maker
Founder, Established since 2019
Céleste Mori
Céleste Mori grew up between Lyon and Kyoto, the daughter of a textile merchant and a ceramicist. She studied fashion buying at Institut Français de la Mode in Paris before moving to Tokyo in 2012 to join the lingerie buying team at a major department store group. After seven years on the floor, she left in February 2019 to found Stream Lab Core Nex, completing a pattern-cutting course in Osaka before producing her first six styles. She is obsessive about cup construction, spends Saturday mornings at Nishiki Market when she is in Kyoto, and keeps a running notebook of every client fitting note she has ever taken.
FAQ
Common questions
How do I know which size to order?
We have a detailed size guide on each product page, but honestly, the most reliable route is a virtual fitting. It takes 30 minutes, it is free, and Céleste or one of our stylists will tell you exactly which size and style will work for your proportions. We have done over 200 of these calls and the fit rate is significantly better than ordering blind.
Do you ship internationally?
Yes. We ship to most countries via Japan Post EMS and DHL Express. Shipping to Europe and North America typically takes five to eight business days. Import duties are the buyer's responsibility. We list estimated duty rates for major destinations on the shipping page.
What is your return policy?
Swimwear and lingerie can be returned within 14 days if unworn, with the hygiene seal intact. We do not charge a restocking fee. Bespoke and made-to-order pieces are non-refundable, but we will always work with you if something is genuinely wrong with the fit or construction.
How long does a bespoke order take?
Six to eight weeks from the point we confirm your fabric choice and measurements. We send fabric swatches before cutting begins, and we ask for a 50% deposit upfront. You will receive one progress update at the halfway point, and we photograph the finished piece before shipping.
Get in touch
Tell us what you are looking for
Fill in the form and we will reply within one business day with a personal note. Not a template. If you would like a virtual fitting, mention it here and we will send you a booking link.
No spam. We reply personally, always.