Rascal Does Not Dream of Logical Witch

"There is another 'me' in this world". Futaba Rio from the science club turned into two person for some mysterious reason. Sakuta hid one of them in his house, not only that, Sakurajima-senpai said she would move into his house as well. Sakuta's vacation was completely messed up. "I hate myself" What's the secret deep in Rio's heart?