Japan is the only Group of Seven country not to recognize same-sex marriage, and Kishida is facing calls for action. Rainbow Family, an organization that supports LGBTQ families nationwide, launched the letter-writing campaign in February.
"We started this project because we feel like we are being ignored by the government. Kids from LGBTQ families are very worried about what's happening right now, and the lack of progress," says Rainbow Family spokesperson Ono Hal.
The group felt compelled to act following a political storm. In February, one of Kishida's top aides said he would not live next to a same-sex couple. He later apologized, but the remark cost him his job.
The incident prompted rallies in Tokyo. There were hopes a bill against LGBTQ discrimination would pass before the G7 summit in Hiroshima during May, but discussions are ongoing.
Waseda University Law School Professor Tanamura Masayuki says the main ruling Liberal Democratic Party is being held back by conservative members entrenched with a traditional view of family values.
"Here in Japan, companies, the private sector, and local governments are all moving to support the LGBTQ community. But when it comes to the political world or at the national level, it's happening very slowly," he explains.
Families in limbo
Change is happening far too slow for families like lesbian couple Ai, 42, and Mari, 36, and their two daughters, aged 7 and 9. They each conceived one of their children with donated sperm. But because they can't get married, and don't have the same surname, the family is in legal limbo.
That creates all sorts of difficulties, and often leads to emotional pain. "When the children got sick and we went to the hospital, I was told to bring her real mother because our surnames weren't the same," explains Mari. "It hurt for them to say this in front of my child."
The family resides in a ward of Tokyo that does not recognize civil partnerships. With two children to raise, Ai and Mari want the same legal protections that exist for heterosexual spouses.
For instance, a marriage registration card is all that's needed to guarantee inheritance if one partner dies. But Ai and Mari had to pay thousands of dollars to prepare their own notarized documentation.
They are urging political leaders to enshrine equal rights for all families. "I really feel our suffering will not be resolved unless the law changes," says Ai. "Please listen to our voices. Our lives are on the line. Our neighbors are starting to accept us. It's just the law that doesn't recognize us as a family."
The couple's youngest daughter wrote a letter to Kishida: "Dear Prime Minister, my friends at school understand I have two moms, but why doesn't Japan? Please explain in a way that a child could understand."
She's still waiting for an answer.