Kyoukaisen no Imuko-san

A forbidden tale you must never witness. Imuko beckons you into the accursed realm. Deep within a secluded forest, a sacred rope stretches across the trees. Beyond it lies a world unlike our own. From that side, a lone girl has crossed over… Her name is Imuko, and those who encounter her are said to meet a dreadful fate. You must not set foot beyond the line. You must not meet her gaze. You must not speak to her.

(Source: Shogakukan, translated)