It's no secret that the anime industry makes heavy use of X-rated fan service to appeal to fans, and it gives a whole new definition to "fan service" as a term. Western fans are used to "fan service" meaning a story including much-desired cameos or character re-introductions, for example. But for anime fans, "fan service" means that the characters, typically female ones, are showing a lot of skin. This is a contentious topic at times, but compromise may be possible.
Source：https://www.cbr.com/anime-fan-service-positive-ways/
