The supporting character's harem is very normal - Chapter 14: Elemental Stone

From the outside, Nana’s life seemed simple. She had everything she had ever wanted: a cute but rascally pair of twin brothers, a best friend, and her own restaurant. Nana couldn’t ask for anything more; she was happy and content in her life.

Stella Wilson, a nice rural lady who went to New York to pursue her Veterinary degree. Also, she works part-time as a pet sitter to a three little cats. Her boss, Alice Adelson instructed her to keep the cats away from the next-door neighbor Sebastian, the billionaire. An Alice cat, however, managed to escape from Stella's care and make the way to Sebastian's property, where caused her trouble. Stella is caught by Sebastian while trespassing his property.Sebastian informs her that she must keep the cat away or else he would punish her. Sebastian has already made the decision that he will going to own her and has stated that she will be responsible for the payment. But it's not in monetary value that he's looking for.