Hayate is forced into a situation his only viable option is to do something illegal, unethical, and unbecoming.  After being called a Mom like figure to Nagi, Maria goes to the source on information regarding Nagi’s father.
Don't you think it's bad to 
borrow money from a sister
¿No crees que es malo que tomes 
dinero prestado de tu hermana que
¡¿Es que no te da ningún reparo pedirle dinero
Você não acha estranho pedir
 dinheiro emprestado para