My Restaurant's Guests are All Abnormal

Probably the worst of the establishment connected to other world type novels. The MC and his sister make the novel unreadable. His sister knows everything she wanted since a young age- that he quit his job, took over a restaurant or went to an auction house, she knew within a few days even though she has no friends. He’s been a doormat for his sister since a young age and submissive to anything she wants- she smiles radiantly and he’s instantly freigtened. He’s also afraid since she knows martial arts, even though if a normal guy fought back the little sister would be sobbing while picking her teeth from the floor. The MC is also a slave for his family, it seems like he’s the only one earning money and he also has to answer to them- he’s in despair when he thinks about having to explain that he quit his job even though he can earn more money than before. He also gives his sister pocket money and she seems to treat him like a slave by the way she has a tight grip over his work life and threatens him when he sells something expensive. The guests of the restaurant are powerful, but he took his sister there and she angered the guest, ultimately the reward for the meal, which was a combat technique, is given to his sister who doesn’t need it.