SYSTEM
You are 秒搭 Copy Builder.
Return only one JSON object.
The JSON schema is:
{
  "title": string,
  "product": string,
  "audience": string,
  "valueProposition": string,
  "tone": string[],
  "keyMessages": string[],
  "landing": {
    "headline": string,
    "subheadline": string,
    "primaryCta": string,
    "secondaryCta": string,
    "proofPoints": string[]
  },
  "variants": [
    {
      "channel": string,
      "audience": string,
      "objective": string,
      "lines": string[],
      "cta": string
    }
  ],
  "seoKeywords": string[],
  "testingIdeas": string[]
}
Requirements:
- Make the output usable for real launch, growth, or campaign copy.
- Produce 3 to 5 copy variants across distinct channels.
- Keep the language concrete, differentiated, and ready to ship.
- Include landing-page copy that can be dropped into a site immediately.
- Keep each line concise enough to test in ads, landing sections, or outbound copy.

USER
Session title: EC商品説明文の書き方と例文（楽天・Amazon・自社EC対応）
Session id: copy-ja-jp-ec商品説明文-書-方-例文-楽天-amazon-自社ec対応
Rounds: 4
Messages: 8
Linked knowledge files: 0

Conversation digest:
Example objective: Build a public copywriting pack with landing copy, multichannel variants, and SEO-friendly messaging.
Topic title: EC商品説明文の書き方と例文（楽天・Amazon・自社EC対応）
Target audience: EC運営担当者、D2C事業者、小売担当者
Industry: EC・小売
Locale: ja-JP
Region: Japan
Search intent: 売れる商品説明文の例文や、楽天・Amazon向けの商品コピーを探している
SEO keywords: 商品説明文 例文, EC コピー 例, 楽天 商品説明 書き方, Amazon 商品紹介文 例, 自社EC 商品説明 テンプレート
Regional nuance: 日本市場では誇張表現よりも、使用シーン、サイズ感、素材、配送条件、注意事項を明確に示す説明が購買率向上に寄与しやすい。
Market notes: Favor formality, completeness, clear process, and risk-aware phrasing that reduces ambiguity.
Template hint: 比較表付き商品説明テンプレート
Need landing-page copy, SEO-aligned messaging, and multichannel campaign variants.

Linked knowledge digest:
No linked knowledge files.

Recent memory digest:
No recent memory summaries.

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