GATE Anime-Planet

On August 20XX, a gate suddenly appears in Tokyo's Ginza district, unleashing a portal where monsters, medieval knights and other fantasy beings come from another world and wreak havoc on Tokyo. The Japanese Defense Force take action against these monsters and push them back into the "Gate". Third Reconnaissance Team is dispatched to the "Special Region" lead by officer (and otaku) Youji Itami. On their travels, they are joined by a beautiful elf girl who is a survivor from the dragon's rampage and guide the group across the dangerous new world. 
On August 20XX, a gate suddenly appears in Tokyo's Ginza district, unleashing a portal where monsters, medieval knights and other fantasy beings come from another world and wreak havoc on Tokyo. The Japanese Defense Force take action against these monsters and push them back into the "Gate". Third Reconnaissance Team is dispatched to the "Special Region" lead by officer (and otaku) Youji Itami. On their travels, they are joined by a beautiful elf girl who is a survivor from the dragon's rampage and guide the group across the dangerous new world. 

Career Gate Manga

Divine Gate Anime-Planet

GATE: Teikoku no Bara Kishidan - Pinya Co Lada 14-sai Manga

The Lost Gate Manga

You Didn't Tell Me the Start of My Transmigration Was a Gate Manga

Steins;Gate 0 Manga

GATE: Featuring the Starry Heavens Manga

Gate of Nightmares Manga

Steins;Gate: Hoshikuzu no Duplet Manga