It sounds like you're referring to — likely a fan game, visual novel, or adult-themed RPG (often found on platforms like DLsite or in indie dev circles). The title combines oppai (Japanese for breasts) with succubus and academy setting, suggesting a lewd/comedy game where the player character navigates a school of seductive demonesses.
Kaito swallowed. The syllabus on his tablet read: Draining Basics, Aura Feeding 201, and Practical Temptation (Daily Lab). oppai succubus academy
Lilyssa giggled. "Most don't."
Kaito tugged his collar. This was going to be a very long semester. Would you like a longer story, character profiles, or help designing game mechanics for such a concept? It sounds like you're referring to — likely