Ranma ½ (1989)

S1E160 Boy Meets Mom - Part One

While at Mrs. Tendo's grave, Ranma reflects on his own mother. He receives a postcard from Nodoka Saotome, expressing her intention to visit. Excited to reunite, Ranma's enthusiasm is dampened when Genma reveals a secret. He explains that he made a vow to Nodoka at Ranma's birth—a life-or-death promise stating that Ranma must be raised as a true man, or they would face dire consequences. To protect their secret, Genma and Ranma concoct a plan to present Ranma as "Ranko," a cousin of the Tendo family, when Nodoka arrives.