The Japanese anime industry has set itself apart from Western animation and live-action TV in many ways, from Disney inspired sparkly backgrounds and large character eyes to shouting attack names and flashy intro credits sequences. Nearly all anime fans love those conventions, while fans are more divided on the topic of anime-style fan service. In this industry, fan service means something more specific than generally giving the fans what they want, such as cameos of popular characters.
Source：https://www.cbr.com/fan-service-in-anime/
