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SEAM
都会の屋上で遠くを見る女性

SALON HAIR CARE BY HOYU, JAPAN

BYKARTEFrom your hair's own chart

The aim: pristine natural hair that has never known damage

18combinations

As many as there are hair types and finishes

The name comes from the medical "karte", the patient chart. The stylist is likened to a doctor for hair who records each person's hair and faces it
Choose the shampoo by hair type, the treatment by finish and leave-in care by texture, from 18 combinations

白いタイルの上のガラスのビーカー

THE TECHNOLOGY

Cystine, the strength of hair

Cystine supports the strength and suppleness of hair. When color and UV reduce it, the inside of the hair turns hollow
hoyu's own CiP SHOT uses cystine's property of dissolving in alkali and setting in mild acid to replenish it inside the hair. It is used in salon treatments; home products keep that finish and prepare for the next treatment

OUR COMMITMENT

What BYKARTE stands for

  1. In the name "karte"A stylist as a doctor for hair: a promise to record each person's hair and face it
  2. Toward natural hairWhat is ideal hair? The answer many salons gave was pristine hair that has never known damage
  3. Four yearsA vision held for ten years, given form over about four. In 2021, as one answer
  4. Spread by word of mouthNot through advertising but through the voices of those who tried it, it has spread quietly and surely
  5. Only chosen salonsOf about 250,000 salons in Japan, only about 1% that have completed training (as announced in 2024–25)
  6. The nano eyeA large electron microscope looks into hair down to a billionth of a meter

WHAT HAPPENS IN YOUR HAIR

Three things that happen in your hair

満たす
01 FillIn the salon treatment, cystine into the hollows of the hair
整える
02 SmoothAn 18-MEA derivative smooths the cuticle
輝く
03 ShineToward soft, natural hair that returns the light

Images are for illustration

THE LINES

A prescription for you

BYKARTE リペアシャンプー CH+

CH+

Repair Shampoo CH+Normal to coarse hair

A soft clean

Shampoo ¥4,180

See details
Ingredients
PPT-type cleansers, keratin and silk-derived ingredients. Free of sulfates and silicones
Sizes and prices
75mL ¥1,320/280mL ¥4,180/600mL ¥6,820
BYKARTE リペアシャンプー FH+

FH+

Repair Shampoo FH+Fine, soft hair

A supple clean

Shampoo ¥4,180

See details
Ingredients
PPT-type cleansers, keratin and silk-derived ingredients. Free of sulfates and silicones
Sizes and prices
75mL ¥1,320/280mL ¥4,180/600mL ¥6,820
BYKARTE リペアシャンプー UH+

UH+

Repair Shampoo UH+Curl and waves

A fresh clean

Shampoo ¥4,180

See details
Ingredients
Sorbitol, sodium saccharin and keratin-derived ingredients work on wavy sections
Scent
Fresh pear with patchouli
Sizes and prices
75mL ¥1,320/280mL ¥4,180/600mL ¥6,820
BYKARTE セラムトリートメント SS+

SS+

Serum Treatment SS+Silky

A finish fingers glide through

Treatment ¥4,180

See details
Ingredients
Repair amino, 18-MEA derivative, meadowfoam-δ-lactone
Sizes and prices
60g ¥1,320/250g ¥4,180/600g ¥7,920
BYKARTE セラムトリートメント MS+

MS+

Serum Treatment MS+Moist

Moist, soft and cohesive

Treatment ¥4,180

See details
Ingredients
Repair amino, 18-MEA derivative, meadowfoam-δ-lactone
Sizes and prices
60g ¥1,320/250g ¥4,180/600g ¥7,920
BYKARTE セラムトリートメント HS+

HS+

Serum Treatment HS+Heavy damage

Moist, smooth, high repair

Treatment ¥4,180

See details
Ingredients
Shea butter and murumuru butter added to the shared repair ingredients
Scent
Grapefruit and a floral bouquet
Sizes and prices
60g ¥1,320/250g ¥4,180/600g ¥7,920
BYKARTE セラムマスク

MASK

Serum MaskOnce or twice a week

Makes the salon finish last longer

Mask ¥2,420

See details
Formula
Repair ingredients shared with the salon care, in a formula that heat helps set
How to use
Squeeze out water well and work it from mid-lengths to ends, about two cherries' worth for medium hair. Rinse, then dry with heat
Sizes and prices
100g ¥2,420
BYKARTE エッセンスオイル

OIL

Essence OilShine and glide

Protects hair from heat and UV

Oil ¥3,300

See details
Ingredients
Ingredients that guard against heat and against UV
Also
Essence milk for moisture and cohesion (95mL ¥3,300), concentrate essence for the ends (40g ¥2,200)
Sizes and prices
95mL ¥3,300

Prices are the maker's list prices including tax (checked October 2026). Ask in store for sizes and other items See all products →

HOW TO USE

The bathroom ritual

  1. CleanseChoose the shampoo by hair type: FH+ for fine hair, CH+ for normal to coarse, UH+ for curl and waves
  2. NourishChoose the treatment by finish: SS+ for silky, MS+ for moist, HS+ for heavy damage. Serum mask once or twice a week
  3. ProtectOn towel-dried hair, essence oil or milk, and concentrate essence on the ends, 1 to 3 pearl-sized drops

IN THE SALON

A prescription for your hair, at the salon

At the salon, a system treatment layers several formulas. CiP SHOT, which replenishes cystine, is a technology used in this treatment
Home care keeps the finish of the treatment and prepares hair for the next one

THE STORY

Quietly, surely

A brand born when hoyu, known for hair color, stepped into the field of repair
Within a simple form, the packaging is particular about surface color and finish. The shampoo pump comes packed in the box

  1. 2021Launched (hoyu, Nagoya)
  2. 2024UH+ and HS+ join, making 18 combinations
  3. 2025Serum mask and concentrate essence
夕暮れの銀座四丁目の交差点

AT SEAM

In Ginza, face to face with your hair

SEAM GINZA is on ONE GINZA 3F, a 1-minute walk from Exit 7 of Ginza-itchome Station
Our staff look at your hair and guide you to the right line and order of use. Tax-free at all 7 stores. Please bring your passport

Find a storeHair Type Finder (3 min, free)See all products