Nazo no Kanojo X

Mikoto Urabe transfers into Akira Tsubaki's class and immediately attracts his attention through sheer strangeness: she barely speaks, sleeps at her desk, and occasionally breaks into laughter for reasons no one understands. After an even stranger incident, Tsubaki discovers that Urabe's saliva has a direct effect on him, to the point that he develops genuine withdrawal symptoms when deprived of it.

To Urabe, this is not an illness but proof of a special bond between them, beginning a romance that follows none of the usual rules of closeness. Urabe keeps her scissors, her secrets, and a careful distance from everyone else, while Tsubaki tries to understand a girl who expresses emotion through a language he has never encountered. The closer he gets, the more he realizes that her mystery is not an obstacle to their relationship so much as something he must learn to read.