Ochikobore Mahoutsukai to Koisuru Kemono

From 2nd Life Scans: Luka was born into a prestigious family known to all wizards. However, he was considered a dropout for his lack of magical ability and treated coldly by his parents. As soon as he graduated from magic school, he was kicked out of his house. He is now barely surviving by selling medicines he concocts. One day, he happens to come across a phantom beast covered in wounds within the forest and treats it. The beast tells him he wants to return the favor and offers him a master-servant contract. Unable to refuse, he ends up signing a contract with Alba, the mythical carbuncle of wealth and fame.