Last melody of Earth

(This my first fanfiction and crosssover as well and based story on the YLIA, Love Live franchise, and all post-20xx Nuclear Holocausts franchise where the both franchise story have shared universe.)

In the Distant future, Kousei Arima has daughter named Karina Arima after he getting married with his first wife. Karina Arima was abandoned daughter after her parents divorce and which led to her being exiled to China. She live abroad peacefully with Chinese family for 6 years until one day she get bad day where everything she known has died and destroyed because of Nuclear Holocaust. Now, the world where she lives in aren't same, unfriendly, and unfamiliar. In order to survive and unite with her family she must travel with her surviving Chinese family to the south to look for clues before around the world since there are still signs of life there.

Will she manage it?

Warning: This is my oc story and there will be more oc since the main character are oc herself.