S-7 Daily Shampoo — Standard Size (16 fl oz / 473 mL)

A daily shampoo developed in San Francisco by a Japanese hairdresser — for people who wash often and want a gentle, balanced clean.

What is S-7?
After about a year of refining in the salon, S-7 is now available in a 100 mL travel size, with the Standard Size in its final packaging and label stage. Formulated with hydrolyzed silk protein for a soft, silky lather, it's a salon-crafted daily shampoo made for frequent washing — leaving hair feeling clean, light, and balanced.

Built for hair that gets washed every day
Most shampoos are designed around two or three washes a week. San Francisco doesn't work that way — morning fog, dry afternoons, the commute, the studio. If you wash daily, the question isn't how strongly a shampoo cleans. It's what's left behind after the seventh wash of the week.
That's the problem S-7 was built around: not one dramatic wash, but the seventh one of the week.

Why S-7 is different

• Made for daily, frequent washing — designed for the reality of washing hair 5–7 times a week, not just once
• Formulated without Cocamidopropyl Betaine (CAPB) — a documented contact allergen for a subset of users (see the story below)
• A soft, silky lather from hydrolyzed silk protein — cushions the hair during wash instead of stripping it
• Sulfate-free — no SLS or SLES, and gentle enough for color-treated and chemically straightened hair
• Salon-crafted and refined batch after batch on real hair, not in a lab

MATSUYAMA
Our house scent: Japanese yuzu over hinoki cypress. Citrus at the top, quiet cedar-like wood underneath. It's built to read as clean rather than perfumed, and it stays in the hair rather than following you around all day.

What's in it, and why

• A sulfate-free cleansing system. Built on cocamidopropyl hydroxysultaine and coco-glucoside, chosen after repeated reformulation on real salon guests rather than on a spec sheet. It lathers properly and rinses clean.
• Hydrolyzed silk protein. Slip and an even feel through the mid-lengths, and a softer lather during the wash itself.
• Sodium lactate. A humectant that helps hair hold moisture through repeated washing.
• Guar hydroxypropyltrimonium chloride and polyquaternium-7. Conditioning agents that make wet detangling easier, especially on fine hair.
• pH adjusted with citric acid. Leaves the cuticle settled after rinsing.

Who it's for

• You wash daily, or close to it, and your current shampoo is starting to show it.
• Your scalp or hands react to products described as gentle, and you've never been able to pin down why.
• You have fine hair that goes flat or feels coated by richer shampoos.
• You've had color, a perm, or straightening, and want something mild enough to use between services.

Two Ways to Start
The 100 mL travel size is available now — the same formula, in the largest bottle you can take through airport security. It's the easiest way to live with S-7 for a week or two before the Standard Size arrives. The Standard Size for daily use is still in final packaging; join the S-7 launch list on this page to be notified the moment it's ready.

The Story Behind This Formula
I've been a hairdresser for 30 years, and for most of that career I dealt with ongoing hand irritation — even while using products I thought of as "gentle." When I started developing S-7, one surfactant I tested and liked for its lather and rinse-feel was Cocamidopropyl Betaine (CAPB) — a very common, well-regarded ingredient in salon products. But the irritation kept coming back, worse than before. So I ran a proper elimination test on myself, isolating one ingredient at a time until I could pin down the cause.
The result was conclusive: CAPB was the culprit. It's since been named Allergen of the Year by the American Contact Dermatitis Society (2004), and it's estimated to trigger a reaction in roughly 3–7% of people patch-tested for it. Since removing it, my own hand irritation has improved significantly — though everyone's skin responds differently, and this is my personal experience, not a claim about how S-7 will affect yours. That's why S-7 is formulated without CAPB from the ground up.

How to Use
Apply to wet hair, massage into a lather, and rinse thoroughly. Repeat if you're washing out product or a heavy day. Follow with a rinse-out conditioner if you use one, then finish on towel-dried hair with No.115 or No.215 before you dry.

A note on your shower floor
S-7 can leave a slippery film on shower floors and tubs. Clean the floor with soap after use — rinsing with water alone won't remove it, and the film becomes slippery again the next time the floor gets wet.

Do you need a conditioner?
If your hair hasn't had a chemical service (color, perm, or straightening), S-7 is typically gentle and moisturizing enough that a separate rinse-out conditioner usually isn't necessary. For extra shine and manageability, we recommend finishing with No.115 or No.215 instead — a lighter, leave-in alternative to a rinse-out conditioner. If your hair has had a chemical service, follow with your regular conditioner or treatment as needed.

The development story
This shampoo wasn't made in a boardroom. Read the development story on masashitt.com →

The Standard Size is currently in final packaging and label development. The 100 mL travel size is available now.