Gakkou no Kaidan 3

The third installment of the "Gakko No Kaidan" series follows the trek of several elementary school students as they wander into an alternate world that exists on the opposite side of a school mirror. Nishida Naomi (the hapless teacher in "Gakko No Kaidan 2") returns as the teacher who accompanies the children on their journey into the surreal universe.
(Source: IMDb)