Living in One Room Apartment with Knightess from the Alternate World

In the apartment of the protagonist, out of nowhere, there was a girl knight. She approached him with the words "this world will be saved, I found you a hero...". However, before he could finish, she noticed that the confused boy standing completely naked with an incredible erection and on the background of the TV hear the erotic moans of the girls. Apparently she has found hero her entire life, but not quite on time. Now he has to live under the same roof with a very extravagant and rebellious woman...