Yumi arrives at the abandoned hospital at 6:45 p.m. on April 24, and it's nighttime. On that date, sunset in Japan ranges from around 6:20 p.m. Japan Standard Time in the east, near Tokyo, to around 6:55 p.m. in the west, near Nagasaki. Depending on what part of Japan she is in, it should be daytime or twilight outside, not full dark.