Isekai no Shugo-Hime wa, Norowareshi Akki no Kiss o Matsu

One night, a student Ryo, tries out a astral projection and is sucked
into a world named MUGEN KAIROU (the corridor of dreams an fantasy).

Floating in the air, in an unknown world, he finally realizes his floating
in mid air is an impossibility and subsequently begins to fall.

A girl in a goth loli dress catches him but his preconception that it is
impossible to defy the laws of gravity is too strong and they both fall.

Just before smacking into the ground, levitation kicks in and they land safely.
"This is my Master? How unreliable----" she mutters under her breath.

Ryo must fight to protect Nina from Klaus and return peace to this world.

[From DLsite English]