My Big Sister Lives in a Fantasy World: Volume 1 by Tsuyoshi Fujitaka

One day, first year high school student Yuichi Sakaki suddenly awakens the power of “Soul Reader” within him, and he can see words above peoples heads that describe their true nature! With just a glance at the people around him, he sees crazy things like “Zombie”, “Witch”, and “Vampire”... That would be bad enough, but then there is “Serial Killer” Natsuki Takeuchi walking straight toward him... Nobody would ever believe him! Well, except for his older sister Mutsuko: This kind of stuff is right up her alley.