Complex sentence: Karin is the protagonist of the series, orphaned at a young age, she was brought up by her aunt, but having no talent in studies and sports she was frequently scolded by her aunt due to her lackluster grades.
Split into simpler sentences: Karin is the protagonist of the series, orphaned at a young age. She was brought up by her aunt, but having no talent in studies and sports she was frequently scolded by her aunt due to her lackluster grades.