When Law got to know about Cora-san's birthday, he was thrilled. He was thrilled like a schoolgirl that had just learned such a great secret about her love. He found it only fitting that Cora-san had been born in the middle of summer; the man's sunny disposition and positive energy could keep a person warm even in the dead of winter, so it was perfectly right. He encircled the date in his calendar - and, much to his embarrassment, he drew a few red hearts around it, too - and awaited it with such an enthusiasm he would've never suspected himself of before.
Then, Law decided that from now on July 15 would be the holiday for the Heart Pirates. They would have a day off, they would celebrate, and maybe he would even let his men do anything they pleased on that particular occasion. There would be booze, lots of good food, and wild festivity; after all, their patron, the very cause and reason why the Heart Pirates had come into being, deserved it. And it was only natural that they would party like crazy; Cora-san had been crazy, wasn't he now?
However, as time drew near, Law noticed his spirit diminished and the date began to disconcert him instead – him, a man who no longer feared anything. When the day finally arrived, he found himself locked in his cabin with a bottle of seaberry liqueur and unable to look anybody in the eye. He could only cry over his foolishness, for he had long ceased crying over his cruel fate. Still, why did it hurt so much even after all those years? He kept swallowing his pain alone, cursing his weakness and praying that the day ended soon - the day that turned him into twelve-year-old who had lost the last thing dear to him and knew it was all his fault. He knew he deserved that and couldn't be consoled by his memory that claimed otherwise.
Afterwards, Law threw the calendar away and forgot all about festivities; no-one needed it. Cora-san that had accompanied them until now was enough. That Jolly Roger. That mark on the coat. The very name of his crew. Those designs on his skin. Ope Ope no Mi in his body and soul. Those words, 'I love you,' kept forever in his heart.
Law decided he would have all time for birthday celebration once they were reborn one day.