Dual timelines explore a Japanese widow's memories spanning post-war Nagasaki in 1950s and England during 1980s Cold War era, unraveling secrets that intertwine her past and present experiences across borders.

The story follows So-hee, a 14-year-old Zainichi Korean girl. She goes to a Korean school and devotes herself to Korean traditional dance as her school club activities. One day, at an exchange event with a Japanese school, she befriends Mirai, a Japanese girl who shares her love of K-pop. Through this encounter, So-hee gradually begins to connect with the world beyond her own. As their friendship deepens, the two decide to sell unused items from So-hee's home on a flea market app to earn money for their favorite K-pop idols live tickets. One item fetches an unexpectedly high price-a North Korean CD, which is So-hee's father's. Sanju, the father, is the principal of a Korean elementary school. Emboldened by this success, So-hee and Mirai take it a step further, eventually selling even the medal that Sanju had been awarded by his homeland, North Korea.

The strange friendship between a boy and a kaiju.