The reader is randomly summoned to a fantasy world by a Princess, and he gets real versions of the kamen rider Grease Gear as a result. The reason the Princess summoned the reader is because the demon lord(a succubus) has gathered an army out of no where.

First chapter: reader is summoned, princess introduces herself, foreign prince barges in angry that a summoned hero is winning his "prize" affection(he sees the princess as nothing but something for him to own). Reader henshins into Grease and kicks the prince's ass.

Second chapter: the reader is taken to a market for equipment for his journey to battle evil, he wonders off and finds a tent, inside, tons of people with animal features in cages, hurt, scarred, covered in evidence of abuse, the princess soon arrives and finds the reader, before looking towards the people, who she Identifies as beast men, showing a bit of discomfort in their presence(her father had always spoken negatively about beastmen). The reader demands why all these people are trapped in cages, starved, and even harmed, even children, express great anger towards the scene before him. (Ends up with three followers, two young Beastman girls, one a tiger, the other a panda, as well as there mother, a lioness.)