Finn used to live in District 4, and his parents died in District 4 as well. However, the block management had deliberately prepared a special place to bury people who died from zombies, including his parents.
That was why he had gone to District 1 every year before officially moving to District 1 from District 4. Today was the day his parents died, and he went to Paradise Hill as usual.
He visited his parents' graves every year, and he was very familiar with the shop that sold flowers. That was why he went to that shop before going to visit the graves so that he would not come empty-handed when he visited his parents again.