What is nazo no konojo x?

"Nazo no Kanojo X" is a Japanese manga series written and illustrated by Riichi Ueshiba. It was serialized in Kodansha's Monthly Afternoon magazine from December 2006 to September 2014 and was later adapted into a 13-episode anime television series by Hoods Entertainment.

The story revolves around a high school boy named Akira Tsubaki, who one day discovers a mysterious girl named Mikoto Urabe napping in class. To his surprise, he discovers that she has a unique way of transferring her emotions to others through her drool. As Akira becomes more and more intrigued by her strange behavior, he decides to taste her drool, which leads to a strange and complex relationship between the two.

"Nazo no Kanojo X" is known for its unique premise and exploration of unconventional relationship dynamics. The series has been praised for its writing, characters, and art style, and has gained a dedicated fanbase both in Japan and internationally.