Dantoudai no Hanayome - Sekai wo Horobosu Futsutsuka na Tatsuki desu ga.

Synopsis:

A "mythical beast" showed up from the compartment that fell before Ryuunosuke Dazai. The vindictively gorgeous "winged serpent", Rinne Irako, was condemned to death as a "disaster" that could obliterate the world and was being moved