Premieres July 2024. Additional cast/staff information in the ANN article. Synopsis from AniList:
A first year high school girl likes a second year boy in her drama club. She acts out various character archetypes that you would find in a typical manga harem as their friendship deepens.
100GF is a comrom though (i.e., more comedy than romance), in my opinion. The whole series is basically a giant meme.