Apparently the author is incapable of drawing different looking girls, so we have been introduced 2 new characters that look EXACTLY like the imouto...
That feeling when a slightly-wacky classmate shows up later as a supervillain. 🤖
I'm sure it was on the list of classic sources of narrative conflict, right? Man vs. nature, man vs. society, man vs. kinky supervillain stalker, etc.