But growing support from the nation's top business lobby and major companies is putting pressure on the government of Prime Minister Fumio Kishida and his conservative ruling party.

Organizers estimated 10,000 people marched in Sunday's parade in the downtown Shibuya district.

Participants said they realized how their nation lagged the rest of the G7 but were hopeful of change.

Activist group Marriage for All Japan opened a booth at the Rainbow Pride festival venue and encouraged visitors to send postcards to parliament representatives demanding recognition of same-sex marriage.

"Before G7, we want the government and parliament to take a big step towards realising same-sex marriage," Takehiro Kato, a member of the group, told Reuters.