the ultimate familiar (familiar of zero harem x OP male oc)

After being rejected by his crush, Toad decides to focus more on his studies. Earning the highest grades in school, he's aiming for a prestigious college. But on his way to the entrance exams, he was sucked into a portal and ended up in another world where he gains the attention of multiple girls and a kind hearted princess who immediately falls in love with him. He becomes a familiar for a small pink haired mage. But being a familiar isn't easy. he is under constant attack by corrupted nobles who abuse their power for their own selfish gain and ended being killed by him. He will get back home eventually. And his crush will finally give him a chance but he will reject her and she will become obsessed with him.

This takes place in an alternate universe. Toad will replace Saito Hiraga. And Louise will be kind hearted and not a stuck up tsundere.