ALcot - Osananajimi wa Daitouryou: My Girlfriend is the President.

It started out as an ordinary morning, woken up by my childhood friend. Had a good breakfast… complete with morning hard-ons. An ordinary, everyday eroge scene. Or… so it seemed. Things would never be the same from that day, as peaceful everyday life was blown to bits.
An accident on a spaceship heading to earth, causes it to crash into the office of the Prime Minister of Japan. The ministers end up in a state too horrible to look at. To avoid chaos, the alien choses a girl who happened to be there, and to make ends meet, brainwashed all of mankind.

Nippon adopts a presidential system overnight, and incredibly, a girl, my childhood friend, is the president. The world will answer to her every whim.