SPOILERS AHEAD!
aaaaaaaaaaaaaaaaa, this game is amazing! I got all the endings (including the hidden ending, though I was a bit confused on how to get it at first). I literally said "what the fuck" during the "true" ending cause of "Senpai's" sudden turn of preference, one of my favorite endings to be honest. After the True Ending I thought about an odd ending: what if Sebastian-Kun was yandere too and killed Yandere-Chan when she tried to save him from Robert?