Haru No Yu's Invincible Life

My name is Kasugano Yu. I have a cute and capable little sister, and I'm a transmigrator in a crossover world.

I have three decks in my hands: FGO, Ultraman, and an unknown deck, plus an extra deck of Kamen Rider. I feel invincible, but I'm still freaking out.

The future looks pretty wonderful... but...

The yandere girl Kotonoha Katsura, the flat-chested upperclassman Kuroyukihime, the artificial angel Ikaros, the fallen angel Gabriel... and that gigantic monster... Can someone tell me what's going on?