I’ve written before about how an affair is only an affair in Japan if you get caught. A recent court case raised a related question: Is an affair an affair if you seriously believed it wasn’t an affair? It’s an important question in a country where an affair with a married person can cost you millions of yen.
A new Supreme Court ruling provides some relief to lovers who claim to have been duped. It asked a lower court to reconsider damages it had awarded to a man who said he had seen proof that his lover was in the middle of a divorce.
How much does an affair cost in Japan?
In Japan, having an affair with a married person can cost you. Japanese civil law holds that a lover can be held liable for damages in the event that a couple divorces in the wake of the tryst.
Now, there are limitations. Three conditions have to be fulfilled:
- There is proof an infidelity occurred
- The partner outside of the marriage knew their lover was married
- The affair resulted in harm to the marriage
If these conditions are met, a wronged spouse can sue, not just their unfaithful spouse, but also the affair partner. If the affair didn’t lead to a divorce, a wronged partner can get 500K to 1 million yen ($3,100-$6,250). If the affair directly resulted in divorce, the financial award can climb up to 3 million yen ($18,750).
However, new precedents have been set over the past few decades that let some Don Juans and Juanitas off the hook. In 1996, Japan’s Supreme Court created a “marital breakdown” defense: you can’t be held liable for the collapse of a marriage that’s already collapsed. This means, for example, you can’t be sued for having an affair with a person already in the middle of a divorce action, because there’s no harm and thus no liability.
In reality, courts rarely accept this defense without strong proof, such as documented divorce intent. But it’s there. Separately, a 2019 Supreme Court ruling limited when an affair partner can be held liable as the cause of the divorce itself.
An overturned financial judgment
Which brings us to the latest intriguing case. A now-50s husband sued his 40-something ex-wife’s affair partner, the head of a restaurant where she had worked, for a cool 3.3 million yen ($20,600).
The thing is, their marriage was already a zombie. By June 2023, the couple had stopped speaking and had confirmed via email that neither objected to splitting. The wife even showed a divorce petition to her lover with her portion filled out. She also showed him an email from the husband in which he said they shouldn’t interfere in one another’s privacy.
The new couple grew close, and the married partners split that November. Despite their agreements, the ex-husband got angry and sued the restaurant manager. In 2025, the second-instance Takamatsu High Court ordered the affair partner to pay 550K yen ($3,400).
The man appealed, saying he wasn’t responsible for the couple’s divorce. On June 5th, the Supreme Court agreed. The court ruled that, if an affair partner has “reasonable grounds to believe the marriage had already broken down,” they bear no fault in the divorce and thus no damages can be awarded.
The Supreme Court vacated the financial judgment and remanded the case back to the lower court.
Navigating the landmines of indiscretion in Japan
Financial penalties aren’t the only negative consequence of having an affair in Japan. Politicians and celebrities are often forced to quit or suspend their activities when caught in a tryst. That happened recently to Ogawa Akira of Maebashi, who resigned after meeting a subordinate 10 times in a love hotel.
Polls show that, while not everyone cares about celebrity affairs, enough people care for it to be career-ending. A recent poll by Locagoo found that around 63% – over half – of people asked said they didn’t find it necessary for a celeb to take a break after news of an affair broke. However, 36.3% of those polled said that these stars should take a break and that they “don’t want to see them.”
Whether you’re a celebrity or not, one thing is clear: if you’re thinking of fooling around with a married partner in Japan, be very discreet. Or, perhaps, wait a few days for the ink to dry on the divorce petition.
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Sources
妻が離婚届見せ不貞行為 不倫相手の賠償、審理差し戻し 最高裁 毎日新聞
「不倫」めぐり最高裁が初判断 「婚姻関係の破綻を信じた理由があれば不倫相手は賠償責任を負わない」 東京新聞デジタル
「離婚」信じ不倫、審理差し戻し 破綻認識なら「過失なし」―相手方男性の敗訴破棄・最高裁 時事ドットコム
不貞行為の賠償命令破棄、最高裁 「破綻信じた理由検討を」（共同通信） Yahoo!ニュース／共同通信
不貞行為における婚姻破綻関係の抗弁 小西法律事務所
不倫は不法行為？不貞行為における慰謝料請求と求償権の注意点 アディーレ法律事務所 新宿支店
Can You Sue a Cheating Spouse’s Lover in Japan? Higashimachi LPC
不倫スキャンダル ⇒ 芸能人は 【活動自粛】 するべきか？ 意外な “世論” が明らかに。 テレビの「気になるギモン」を独自調査 Lasisa