East Tower by roseVeRte is an episodic visual novel series that is available for smartphones and computers; now also officially in German (with Japanese voice acting). The game is divided into 4 paths; Akio, Takashi, Kuon, and Kurenai. Each episode is about one of the four boys and you’ll learn more about the plot. It is recommended to play the series in the shown order.
The game is not only an otome game, it is also very funny and romantic. Since the female protagonist changes her gender in the virtual world, there will also be funny BL scenes. You can buy the episodes here on Steam: