Ryo

Pre-Timeskip - The Heart Pirates Trafalgar Law’s crew name and association with hearts can be easily connected to Corazon, though at the time of Law’s introduction, there is no indication that this theme was inspired by another character. Oda likely didn't have Law’s exact history in mind way back in Sabaody (he did admit to designing all of the new supernova pirates in a rush, and was later surprised by Law’s overall popularity). Some kind of connection to Donquixote Doflamingo was plausible, at least, given the similarities of his and Law's Jolly Rogers. ♡ ︎ Chapter 666 - "I'm free to go wherever I wish."

This statement from Law during the Punk Hazard arc could be considered a very early reference to Corazon, the person Law credits for giving him such freedom. Oda probably didn’t have Corazon’s character or role fleshed out at this point, but it’s clear that Law is keenly aware of his independence and values it greatly. On re-read, this panel serves as a subtle foreshadowing of Law's cherished savior. ♡ ︎ Chapter 690 - Law's Trauma

In this scene, Doflamingo mocks Law for his Vergo-related trauma. It is not even hinted that a third party was involved in this incident, so we still can’t say if Oda had Corazon in mind yet. At this stage, readers can deduce that Law won his freedom from the Donquixote pirates and doesn’t intend to return to them. The “heart seat" having been saved for Law is also mentioned near the end of the Punk Hazard arc, casting Law as someone Doflamingo may see as a wayward son. Earlier discussion between Doflamingo and Vergo imply that Vergo and Law possessed a deeper familiarity than what is eventually written for Law's backstory. Interestingly, the traumatic incident Doflamingo alludes to ends up being directly related to Corazon. Thus, on the re-read, this line becomes another early reference. ♡ ︎ Chapter 704 SBS - Heart-themed tattoos

The Dressrosa arc is where Law’s distinctive chest tattoo makes its first canonical appearance. In the SBS (the manga's Q&A segment), Oda acknowledges the heart theme while playfully hinting at a deeper meaning. Corazon's role has likely been determined at this point, and Oda will now be gradually working toward the character's reveal, nearly sixty chapters later! ♡ Chapter 705 and on - The Corazon Jacket

Similar to Law's chest tattoo, his iconic Corazon jacket also makes its first appearance early in the Dressrosa arc. Oda acknowledges in SBS 768 that the jacket was custom-made as a tribute to Corazon. ♡ Chapter 724 - "Thirteen years ago"

A little further into the arc, it is revealed that Law actually seeks revenge on Doflamingo for a specific incident from thirteen years ago. A third party is not yet mentioned, but we now have a more specific time frame. ♡ Chapter 725 - "Someone's long-held desire"

Though he is not mentioned by name, Law finally makes a direct (and quite passionate) mention of the person whose goal he is trying to fulfill. ♡ Chapter 729 - "'The D will always cause another storm'!!!"

Near the end of Law and Doflamingo's battle on the bridge, Doflamingo asks why Law puts so much trust in the Straw Hat pirates, with whom Law has since formed an alliance. While Law's interest in the D initial is obvious (and could offer motivation for saving Monkey D. Luffy during the Marineford war), the words he imparts to Doflamingo are cryptic. It remains unclear what Law's personal connection to "D" is (in the manga, it has not yet been revealed that Law is a "D" himself) or who exactly he is quoting. ♡ Chapter 729 - "Cora-san...!!"

The first mention of Corazon by name comes in the form of Law's presumed dying thoughts after being shot by Doflamingo. Though, it is not the literal name "Corazon" but rather the nickname Law uses for him: Cora-san (the official English translation omits the honorific). ♡

Chapter 749 - "someone that I loved!!"

Twenty chapters after "Cora-san", more description is finally revealed. Law describes Cora as someone that he loved who was murdered by Doflamingo (explaining his motive for revenge), drops the codename "Corazon" (the same word that has been emblazoned on his jacket all this time), and divulges that Cora was a member of the Donquixote Family. Not only that, but he was even Doflamingo's younger brother! ♡ Chapter 752 - "I was saved!!"

In this scene, Law emphatically defends himself as Doflamingo insults his character. This is one of the first mentions of Law being "saved" by Corazon (after Law telling Luffy that Corazon "gave him his life"), as well as the first utterance of Corazon's name by Doflamingo. ♡ Chapter 760 - Doflamingo's memory

At the end of chapter 760, shortly before Law's backstory chapters begin, Doflamingo monologues about his early hardships. During this brief insight into his past, a panel that depicts the day of his mother's death is shown. On the bed, the silhouette of a small boy can be seen mourning. While not his true first appearance, it's the first official glimpse of Corazon! ♡ Chapter 761 - "The reason I'm alive"

A couple of panels before the backstory chapters begin, Law makes one more mention of his savior, stating that the reason he is alive now is because of Cora-san. ♡ Chapter 761 - Corazon's entrance (and what an entrance it was!)