Most likely, you’re referring to — meaning hidden camera / voyeuristic photography — combined with “harem” (a group of love interests). If so, that points to a niche adult / ecchi genre where the protagonist secretly observes or photographs a harem of female characters.
Here's a report on the Tousatsu Harem genre: tousatsu harem
Some notable examples of Tousatsu Harem anime and manga include: Most likely, you’re referring to — meaning hidden
The tousatsu harem genre is not well-defined, and its origins are unclear. However, it is likely that the genre emerged as a fusion of tokusatsu and harem anime/manga in the early 2000s. Some early examples of tousatsu harem include the Japanese TV series "Kamen Rider" and "Ultraman," which feature male protagonists with superhero powers and occasional romantic subplots. However, it is likely that the genre emerged
Tousatsu Harem has garnered significant attention from fans, particularly among the Japanese online communities. The subgenre has inspired numerous adaptations, including anime, manga, and live-action dramas. Some notable TV anime adaptations include "Koisuru Boukun," "Hakumai Shoujo," and a live-action adaptation of "Kyoukai no Miko."