經典動漫《金肉人》的作者「蚵仔煎（ゆでたまご）」與日本知名連鎖餐飲品牌吉野家之間的恩怨，堪稱日本動漫與商業界交錯的經典案例，歷時數十年，從最初的互惠合作逐步演變為公開的商業裂痕。這段歷史不僅反映動漫作者與品牌之間微妙的利益關係，也展現文化IP在商業化過程中可能面臨的信任挑戰。

在1980年代初期，吉野家曾面臨經營困境，接近破產邊緣。當時，《金肉人》的作者嶋田隆司出於對吉野家個人的喜愛，決定在漫畫中安排主角「金肉人」大唱牛丼之歌，為吉野家進行免費宣傳。這一舉措成功引發全國性的牛丼熱潮，帶動店鋪客流量和營收，最終幫助吉野家轉虧為盈。這段時期，作者與吉野家建立表面上的互惠關係，吉野家也因此對《金肉人》IP懷有感激之情。

然而，矛盾的種子在2008年逐漸萌芽，當時正值《金肉人》29週年（「29」在日語中諧音「肉」）。出版社曾邀請吉野家共同慶祝，但吉野家當時態度冷淡，甚至公開表示「我們覺得沒什麼好慶祝的」，令作者感到被忽視和心寒。緊接著，一樁曾經承諾的「免費牛丼碗事件」更將裂痕擴大：吉野家曾保證贈送作者一個刻有名字的專用餐碗，並承諾「拿著這個碗去全日本門市都能免費用餐一輩子」。然而，在電視節目現場測試時，店員拒絕讓作者免費用餐，讓嶋田隆司在鏡頭前陷入尷尬，對此感到極度失望。這些事件累積下來，使作者對吉野家的信任徹底崩解，並公開表態拒絕再與其往來。

自此之後，嶋田隆司將合作重心轉向吉野家的競爭對手，包括Sukiya（すき家）及なか卯（Nakau），展開長期的商業合作，並透過這些渠道延伸《金肉人》的品牌影響力。雖然與吉野家存在心結，但《金肉人》IP本身依舊保持長青之勢。從2024年到2026年初，新的動畫系列《金肉人：完美超人始祖篇》在各大平台播出，持續吸引老粉絲與新觀眾的關注，也再次證明這個經典IP的市場生命力。

總體而言，《金肉人》作者與吉野家的恩怨，不僅是一段關於商業合作與信任的歷史，也折射出日本動漫產業與企業品牌在跨界合作中可能遭遇的利益衝突與文化摩擦，對後續IP合作策略提供寶貴的案例參考。

The long-standing feud between the creators of the classic anime Kinnikuman, “Yudetamago” (嶋田隆司 & 中井義則), and the famous Japanese fast-food chain Yoshinoya is a quintessential example of the complex interplay between anime culture and business in Japan. Spanning decades, this saga evolved from an initially mutually beneficial relationship to a highly publicized commercial rift, highlighting not only the delicate balance between anime creators and corporate brands but also the challenges of trust in the commercialization of cultural IP.

In the early 1980s, Yoshinoya faced severe financial difficulties and was on the brink of bankruptcy. During this period, Yudetamago, personally fond of Yoshinoya, featured the protagonist Kinnikuman singing a promotional song about beef bowls (gyūdon) in the manga, effectively providing free nationwide publicity for the chain. This move sparked a nationwide boom in beef bowl sales, increased customer traffic, and ultimately helped Yoshinoya return to profitability. During this period, the relationship between the author and Yoshinoya appeared mutually beneficial, and the brand expressed gratitude toward the Kinnikuman IP.

However, tensions began to surface in 2008, coinciding with the 29th anniversary of Kinnikuman (the number “29” in Japanese is a pun for “meat”). The publisher invited Yoshinoya to celebrate the milestone, but the company responded coldly, publicly stating, “We don’t see much to celebrate,” which deeply disappointed the creators. The situation worsened due to the infamous “free beef bowl bowl” incident: Yoshinoya had previously promised to gift the author a personalized bowl, guaranteeing that he could use it to eat for free at any store in Japan for life. Yet, during a live TV segment testing this claim, store staff refused to honor the promise, leaving Yudetamago embarrassed on camera and further eroding trust. These cumulative incidents led the creators to publicly declare their refusal to work with Yoshinoya again.

Following these events, Yudetamago shifted their collaborations to Yoshinoya’s competitors, such as Sukiya and Nakau, establishing long-term commercial partnerships that helped extend the Kinnikuman brand’s influence. Despite the unresolved tension with Yoshinoya, the Kinnikuman IP has remained enduringly popular. From 2024 through early 2026, the new anime series Kinnikuman: The Perfect Origin Saga aired across multiple platforms, attracting both long-time fans and new viewers, reaffirming the franchise’s lasting market appeal.

Overall, the Yudetamago–Yoshinoya saga illustrates how business collaborations in Japan’s anime industry can be complicated by issues of trust and cultural differences. It serves as a valuable case study for IP management and cross-industry partnerships, highlighting the potential conflicts and lessons for future collaborations.