would recomend life changing choices before my bully is my lover, takes place 2 years prior and shares several characters and an overarching backstory a point. neither game is finsihed but at least you know who some of the players are.
if you like serenity, n2 also has a new project, last human which is also good (also a neko harem) and its a parallel dimension of serenity (and oppai oddysey)