"Isekai" and "tonkusatsu" are among the 23 Japanese words added to the Oxford English Dictionary as part of its March 2024 update. While their inclusion may have a special effect, the words are not entirely lost in a brand new world.
According to the OED website, there are at least 574 Japanese loan-words that have been added to date. These new words were added thanks to a collaboration between Oxford University and the Tokyo University of Foreign Studies.
Some of the new words added to the dictionary are the following:
Isekai (noun): A Japanese genre of science or fantasy fiction in which a main character is transported to a different, strange, or unfamiliar world. Often used as a modifier to describe media that falls into the genre. Notable examples include anime series such as "KonoSuba: God's Blessing on this Wonderful World!" and "Aura Battler Dunbine."
The genre is believed to have first emerged in Japan with the 1975 Haruka Takachiho novel "The Warrior from the Other World (Isekai no Yushi)," but the word's usage to describe the genre developed during the early 2000's.
Tonkusatsu (noun) - A genre of Japanese film or television, usually live-action, that is characterized by the use of practical special effects. Such media often features things like giant monsters, transforming robots, and costumed superheroes.
Notable examples would include series such as "Ultraman," "Godzilla," and "Super Sentai," which was adapted for the U.S. as "Power Rangers."
Mangaka (noun) - A writer or illustrator of manga, or Japanese comics.
Notable examples of mangaka include figures such as Akira Toriyama (creator of "DragonBall"), Kazuki Takahashi (creator of "Yu-Gi-Oh!"), and Kentaro Miura (creator of "Berserk").
Other words added to the list include a number of food items, such as takoyaki, onigiri, and katsu. You can find the full list of added words here.
