- In 1945, the United States military dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki.
- Okinawa is mentioned in tandem with other pre-War conflicts such as the Battle of Anchorage, Antietam and Amiens in the Fallout 76 intro.
- In the Museum of Freedom, a placard mentions the shores of Iwo Jima.
- The Pioneer Scouts codebreaker exam provides Japanese as a possible answer to the question, "Which of these patriotic languages did our fine fighting men use as an unbreakable code during World War II?" The Pioneer Scout herpotologist exam also mentions the Japanese giant salamander. Mount Fuji, a major volcano on the island, is an incorrect answer to one of the questions in the Pioneer Scout exams.
- The Watoga High School marching band was set to go on a field trip to the country before the war.
- Two adolescent girls in the Clarksville area, known to have spent a lot of time near a local river, went missing. Calvin van Lowe suspected that they might have been taken by "Kappas," Japanese mythological creatures that "lure children to a watery death."
- In 2241, some descendants of the Yakuza, the pre-War Japanese mafia, inhabit the area around New Reno. They carry short swords known as wakizashi.
- In 2277, Toshiro Kago, a samurai is found aboard Mothership Zeta by the Lone Wanderer after being abducted by aliens.
- Weapons of Japanese ancestry such as katanas can be found in the Mojave Wasteland.
- Some robots seen in the Commonwealth speak Japanese. In 2282, Takahashi, a Protectron, has been set up to work at Power Noodles. The only thing he can say is "Nan-ni shimasu-ka?" (なんにしますか？) or "What will you have?" The mayor notes that this could be due to malfunction. The companion Curie will ask Takahashi about the menu. When he responds with his usual greeting, she will introduce herself to him in Japanese, saying "Watashi wa Curie desu" (私はキュリーです) which means "I am Curie."
- Fallout 4 intro
- Question: "Alfonso took a trip to Europe and saw the ruins of Pompeii. He learned that a famous volcano erupted, and buried the city in ash. Which volcano?"
Answer: "Mt. Fuji"
(Pioneer Scout archaeologist exam)
- Watoga High School school announcer: "Students are reminded to encourage their parents to participate in the "Bake Off Take-Off" to raise money for plane tickets for the Marching Band's trip to Japan."
(Watoga High School PA system)
- Unsolved: Missing girls