|Oscar Joaquín de la Rosa|
|Base of Operations||Mexico, Human World|
|Relatives||Yasutora Sado (Grandson)|
|Manga||Volume 5, Chapter 39|
Oscar Joaquín De la Rosa was Yasutora Sado's grandfather. After the death of Chad's parents, he raised him in his native Mexico until his death.
De la Rosa is a muscular older man with gray hair. He wears purple cap with a yellow shirt and black suspenders.
De la Rosa appears to be a strong and sturdy old man, but with a gentle character. It was De la Rosa's teachings that changed Chad, once rebellious and violent, until he chose a path of non-violence, even to the point of not standing up for himself when attacked.
When Chad's parents both died, De la Rosa, his only relative, adopted him and brought him to live in Mexico. During his early years, Chad was extremely violent; exploiting his advantage in size and strength, he intimidated and bullied any other children who annoyed him. Oscar Joaquín tried to teach Chad to be gentle, but was initially unsuccessful. One day, the fathers of the children Chad fought, seeking to punish Chad, attacked him. Oscar Joaquín stepped in between them, taking Chad's punishment without retaliation. Chad was inspired by this example to become a decent person. To commemorate the event, De la Rosa gave Chad a golden Mexican coin to be kept as a lucky charm. When De la Rosa died, Chad made a vow that he would never fight unless it was to protect others, as instructed, even if his own life was in danger. The coin would come to symbolize this vow, which Chad now claims to hold more value than his own life.
Flashbacks of Oscar Joaquín appear to Chad several times:
Agent of the Shinigami arc
During his fight against Bulbous G, Chad takes a hit and loses consciousness. He then has a flashback of De la Rosa asking him what is the point of his big fists. He tells Chad to think about the sake for which such strength was given to him.
Soul Society arc
During his fight with Shunsui Kyōraku, Chad recalls a promise he made to Ichigo while they were both in junior high, to fight for each other if ever the need should arise. It is then that he also recollects an event in which his grandfather saved him from the wrath of some vengeful fathers and gave him the Mexican coin he holds so dear, the symbol of the vow he took upon himself - not to fight for his own sake - and of his promise to Ichigo. 
Hueco Mundo arc
During his fight against Gantenbainne Mosqueda, Chad claims that his grandfather's spirit resides in the true form of his right arm; the right arm of the giant is in fact a shield meant for the protection of others.
Zanpakutō Unknown Tales arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.
When Muramasa makes it to the Human world he is intercepted by Chad and Uryū. While Uryū is kept busy by Senbonzakura, Muramasa uses his illusory powers to create an illusion of Oscar Joaquín within the familiar surroundings of Chad's childhood in Mexico. Then, while in the image of Oscar Joaquín, Muramasa punches Chad in the gut, incapacitating him for the remainder of the fight.
- The coin Oscar Joaquín gave his grandson was minted sometime between 1823 and 1905. It has the words "Republica Mexicana" (Mexican Republic) engraved on it, as well as the Mexican National Emblem. The monetary reform of 1905 minted Mexican coins with the words, "Estados Unidos Mexicanos" (United Mexican States) that are seen on the Mexican peso today.