Honkai: Star Rail, If They Live Too Long, They'll Turn Yandere

Su Yi, a transmigrator who arrived in this world alongside the Dusk Beast, was deeply depressed. A good person like him had transmigrated into this world! And then he lived on, depressed, to this day. He didn't want to talk much about the past, because he was too depressed. And... the women he knew didn't seem quite right either. This was supposed to be a normal Honkai: Star Rail world... right? "Everyone, I think we can all calm down. Please give me back my scalpel. I am a doctor, after all." ... "I never meant to do so many things, but you know how it is. When you get old, you start to feel your strength failing, especially when you're an old man who's lived through more than two thousand Amber Eras." "And don't ask me how much more than two thousand." "Anyway, only those blockheads, the Dusk Beasts, saw the stuff I pulled back then. They don't have brains, and there's no evidence, so don't speculate about my age."