Gin shimochiai is an expert babysitter, who's willing to make every child in the world happy.
But, actually she's a man disguising as a woman. Inspired by his nanny in childhood and the story of Mary Poppins, he build Poppins Shimochiai Club, a babysitter agent. With his "poppins magic", he can solve every family problem and bring happiness to the children.

source: https://www.mangaupdates.com/series/2feyncx/babysitter-gin