To get a local council here to grant symbolic recognition to same-sex couples, the main pitch wasn’t about civil rights but about sharpening the ward’s cutting-edge image at home and abroad: “We need to be on par with London, New York and San Francisco as a cultural center,” said Ken Hasebe, who pushed the issue for 3 years as an assembly member in Tokyo’s Shibuya district.

His success this spring in passing the ordinance—the first of its kind in Japan—illustrates how changes under way in the West are having ripple effects elsewhere, even in deeply conservative countries like Japan. Many activists see the ordinance as a monumental step, however, because it has helped ignite a public discussion about long-ignored issues such as antigay discrimination.

Mr. Hasebe said he avoided painting same-sex partnerships as a human-rights issue to appeal to a wider audience and avoid arguments with conservative assembly members.

“I told them, only we, Shibuya, could be so bold and diverse,” the 43-year-old said in an interview. The ward, with about 200,000 residents, is known for its street fashion and youth culture, but isn’t considered a particularly gay area. Not only did the strategy work in the assembly, but Mr. Hasebe also pulled off a surprise win in April’s elections for ward mayor, beating a candidate from an established party who wanted to roll back the same-sex recognition. Read More