Hiroko is a 21-year-old former schoolteacher turned factory worker living in Nagasaki during World War II. Fluent in German and deeply interested in the wider world, she holds cosmopolitan ideals and dreams of a life free from wartime restrictions. After surviving the atomic bombing, she carries bird-shaped burn scars on her back, a physical mark that shapes her future interactions as she travels to Delhi and begins building new connections.

Raza is the son of Hiroko and Sajjad, growing up in Karachi as a teenager who struggles with his multiracial, half-Japanese identity. Exceptionally gifted with languages but prone to test anxiety, he desperately seeks belonging in a community that views his background with suspicion. His desire for acceptance leads him to blur lines of identity and seek connection in politically volatile environments.

Sajjad is a young Muslim man living in Delhi who works as a clerk for James Burton. He loves his home city and feels ambivalent about the rising political tensions preceding the Partition of India. Intelligent and culturally open, he shares an appreciation for history and language that draws him toward Hiroko when she arrives at the estate.

Harry is the son of James and Ilse Burton, growing up from an English boarding school student into an adult working in covert intelligence operations. Initially an idealistic recruit, his involvement in proxy wars and espionage slowly wears down his optimism. He cares deeply for the Ashraf family but struggles to reconcile his personal affections with his politically fraught career choices.

Ilse is Konrad's half-sister, living in Delhi as Elizabeth Burton to obscure her German ancestry during World War II. Unhappily married to James, she feels restricted by British colonial society and the conservative social norms expected of her. Her encounter with Hiroko sparks a deep friendship that helps her rediscover her true identity and seek personal liberation.

Kim is Harry's daughter, an American engineer whose desire to control variables stems from an underlying anxiety about the unpredictable world. Raised with liberal values, she tries to be culturally sensitive but finds her worldview challenged by global conflicts, leading to an increasing reliance on structured rules and national security protocols.

James is a wealthy British attorney living in India. He perfectly embodies the attitudes of the British Empire, viewing local customs and people with a paternalistic mindset. Though he genuinely values his clerk Sajjad, he cannot overcome his classist prejudices or bridge the growing emotional distance in his marriage.

Abdullah is a young Afghan refugee living in Pakistan who is deeply affected by the devastation of his homeland. Passionate and fiercely loyal to his roots, he forms a significant bond with Raza, unaware of Raza's true background. His trajectory reflects the broader displacement caused by geopolitical conflicts as he seeks a safe haven while remaining attached to his faith.

Konrad is a 29-year-old German expatriate living in Nagasaki during World War II. He envisions a world where people of diverse backgrounds coexist peacefully, a dream he records in his hidden notebooks. He loves Hiroko deeply and serves as the catalyst for her subsequent journey and the interconnected lives of two families.

A friend of Konrad and Hiroko in Nagasaki. Fearful of the rising suspicion during the war, he distances himself from foreigners, though he steps up to support Hiroko in the immediate aftermath of the city's devastation.

Sajjad's mother, a traditional Muslim woman living in Delhi. Following the death of her husband, she focuses intensely on securing proper marriages for her sons amid the shifting political climate.

The Muslim butler working for the Burton family. He eventually faces the terrifying consequences of the Partition riots, deciding to flee to Pakistan for his life.

Sajjad's older brother. He advocates for moving to the newly formed Islamic state of Pakistan, showcasing the divided paths families take during political upheaval.

One of Sajjad's brothers, who seeks permission to take a second wife or divorce his current one amid the broader geopolitical crisis facing his family.

Ilse's cousin living in New York City. As an openly gay man, he shares Ilse's sense of being an outsider and represents a more liberated existence that she aspires to join.

A neighbor staying near the Burtons' summer home in India. His car inadvertently aids Hiroko and Sajjad when they decide to sneak away to formalize their relationship.

Raza's friend in their Karachi neighborhood. He serves as a connection to the local community that Raza desperately wants to fit into.

Bilal's sister and the object of Raza's teenage crush. Her family's fears about Hiroko's past radiation exposure complicate her secret phone interactions with Raza.

Bilal and Salma's mother in Karachi. She reflects the neighborhood's protective attitudes regarding Hiroko's history and its potential genetic effects.

A local asset working with covert intelligence operations in Pakistan. He operates within the dangerous black market of weapons smuggling, complicating Harry's missions.

An intelligence operative who works alongside Harry. He takes a deeply cynical, suspicious approach to foreign policy and questions the loyalties of local translators.

Abdullah's brother, who participates in the movement of fighters and supplies in the region to support their homeland.

Another of Abdullah's brothers, who remains in Afghanistan. He adapts to the shifting political regimes in the country to ensure his family can survive the ongoing unrest.

A Pakistani taxi driver in New York City. He provides Hiroko with a sense of connection and solidarity among the diverse immigrant working class in the city.

Raza's cousin, named after Sajjad Ali Ashraf. He works in the military and uses his position to provide Raza with crucial regional information.