Shinsou Makou Shoujo 3: Midara na Shokushu no Kairaku ni Aegu Rokunin no Touki

Eldrich and monstrous beings, Ikaiyo feed on humans' rationality.
Against them are six heroines wearing Shinso, suits specialized in fighting Ikaiyo.

Shinso are very skintight for the heroines' physical performance with great flexibility and durability.
No attacks can tear Shinso! Which means, however, they can be just fetishistic costumes
when the heroines are entangled by monsters. Shinso's features can be utilized for rather sexual purposes.

Skillfully wriggling tentacles, slimy aphrodisiac fluid, and their skintight suits...
All of them turn on the heroines' supple skins and eventually erogenous zones...

[From DLsite English]