Mishima Rin wa Shinjinai!

From MangaHelpers:

Ghosts. UFOs. Curses. Mishima Rin despises such supernatural occurrences. She is a child genius with an IQ of 200, and she is determined to disprove all supernatural events through science and technology. She sets up a school "club," which she uses to collect data and conduct research. Out of slight curiosity, Akutagawa Shutaro joins her club… which he immediately regrets. Now, Shutaro is basically her servant. These two will unravel the supernatural mysteries and horrors of their school and town.