Food · Fermented foods
Junsai (Water Shield)
じゅんさい (Junsai)
Also known as: Junsai, Water shield, Brasenia schreberi, 蓴菜
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| Category | Food |
|---|---|
| Japanese labeling name | じゅんさい |
| Common Japanese notations | じゅんさい, 蓴菜, ジュンサイ |
| Origin | Water shield (Brasenia schreberi); aquatic plant harvested by hand from natural ponds (notably Mitane-cho in Akita); the unfurled young leaves are coated in a distinctive jelly-like mucilage; principal modern production Akita Mitane-cho (over 90% of domestic supply, GI-protected as Mitane-junsai) |
| Typical functions | Premium kaiseki and traditional Japanese cuisine signature, Sumashi-jiru clear soup ingredient, Vinegared (sunomono) and chilled summer dishes, Premium gift retail (Mitane-junsai GI specialty) |
| Regulatory status in Japan | Standard agricultural product labeling. Mitane-junsai (Akita) is GI-protected. Volume is small artisanal scale. Not a designated allergen. |
Junsai (じゅんさい / 蓴菜) — water shield (Brasenia schreberi) — is a distinctive Japanese aquatic specialty vegetable, hand-harvested from natural ponds. Akita Prefecture's Mitane-cho is the dominant production region (over 90% of domestic supply, GI-protected as 'Mitane-junsai'), with hand-harvesting from boats remaining the traditional method. The OEM positioning is exclusively premium specialty: as a kaiseki and traditional Japanese cuisine signature (the distinctive jelly-mucilage coating provides unique mouthfeel — slippery, cool, slightly umami), as a sumashi-jiru clear soup ingredient, as vinegared sunomono and chilled summer dishes, and as a premium Mitane-junsai gift retail specialty. Total volume is small.
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Classification
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Product applications
Functions
Regulatory tags
Origin
Common OEM product categories
Finished-product categories where Japanese OEM manufacturers commonly formulate with this ingredient.
- Fresh junsai (very limited summer season, June-August)
- Pre-packed junsai in mineral water (Mitane-junsai standard format)
- Frozen junsai (extending availability)
Ingredient profile
Junsai is Brasenia schreberi, an aquatic plant. The young unfurled leaves and stems are coated in a distinctive jelly-like mucilage (composed of polysaccharides), giving them a unique slippery, cooling mouthfeel.
Production: Akita Mitane-cho (over 90% domestic) is GI-protected as 'Mitane-junsai.' Hand-harvesting from boats remains the traditional method.
Brief summer season (June-August). Pre-packed in mineral water for retail.
OEM applications
Premium kaiseki and traditional Japanese cuisine signature.
Sumashi-jiru clear soup ingredient.
Vinegared (sunomono) and chilled summer dishes.
For OEM: pre-packed junsai retail (Mitane-junsai GI premium positioning), foodservice ingredient supply for kaiseki and ryotei, summer seasonal premium gift retail.
Regulatory classification in Japan
Standard food labeling. Mitane-junsai (Akita) GI-protected designation.
Hand-harvested artisanal production.
Junsai is not a designated allergen.
Regulatory classification in other markets
| EU | Niche specialty positioning. |
|---|---|
| USA | Niche specialty positioning. Brasenia is also native to North America (water shield) but not commonly eaten. |
| China | China has its own junsai tradition (莼菜 / chúncài). |
| Korea | Niche specialty positioning. |
Market reference formulations
Example finished products will be added after verification of Mitane GI origin and product format.
All brand names and product names referenced anywhere on this site are the property of their respective owners. Example entries are provided for informational purposes only and do not imply endorsement.
Seasonality & supply calendar
- Harvest months
- May – August
- Peak supply
- June – July
- Off-season
- September – April (no fresh supply; 水煮 jar / can stock available)
Source: 農林水産省 山菜・水生植物統計. Akita 三種町 (>90% national), Yamagata 庄内 are the only commercial sources. Hand-harvested from ponds.
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Quick answers
- What is Junsai (Water Shield)?
- Junsai (じゅんさい / 蓴菜) — water shield (Brasenia schreberi) — is a distinctive Japanese aquatic specialty vegetable, hand-harvested from natural ponds. Akita Prefecture's Mitane-cho is the dominant production region (over 90% of domestic supply, GI-protected as 'Mitane-junsai'), with hand-harvesting from boats remaining the traditional method. The OEM positioning is exclusively premium specialty: as a kaiseki and traditional Japanese cuisine signature (the distinctive jelly-mucilage coating provides unique mouthfeel — slippery, cool, slightly umami), as a sumashi-jiru clear soup ingredient, as vinegared sunomono and chilled summer dishes, and as a premium Mitane-junsai gift retail specialty. Total volume is small.
- What is the regulatory status of Junsai (Water Shield) in Japan?
- Standard agricultural product labeling. Mitane-junsai (Akita) is GI-protected. Volume is small artisanal scale. Not a designated allergen.
- What products typically use Junsai (Water Shield)?
- Fresh junsai (very limited summer season, June-August) / Pre-packed junsai in mineral water (Mitane-junsai standard format) / Frozen junsai (extending availability)
- Where does Junsai (Water Shield) come from?
- Water shield (Brasenia schreberi); aquatic plant harvested by hand from natural ponds (notably Mitane-cho in Akita); the unfurled young leaves are coated in a distinctive jelly-like mucilage; principal modern production Akita Mitane-cho (over 90% of domestic supply, GI-protected as Mitane-junsai)
- What is the INCI / JSCI labeling name for Junsai (Water Shield)?
- JSCI: じゅんさい
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References
- 文部科学省 (Ministry of Education, Culture, Sports, Science and Technology) Standard Tables of Food Composition — じゅんさい 水煮びん詰
- Akita Mitane-junsai GI documentation
Last updated: 2026-04-28. Ingredient entries are reviewed at least annually against current regulatory listings.