He has seen the world age.
His memories are blanketed in dust. The memories of youth and love and sword are faded and ragged at the edges, like a yellowed piece of parchment fluttering in the breeze. He remembers, somewhat. They seem so old and foreign, like another person's tales that had slowly woven into his mind. But he remembers laughing and playing in the hot springs, getting burned a few times but eventually toughening into stone. He remembers the feeling wound up in his chest when he first gazed upon his rival, knowing that they would be fighting until the rising sun finally set. Those feelings were strong. He would never forget those.
People come to him, asking for advice and lessons. They wish to speak to the Beast – the old guard – the gatekeeper of the past. He still doesn't know if he should feel proud or depressed. He gives them all he can, from spars to words to pats on the back. But there is only so much he can do. He is not a god like some people seem to treat him; he is just a man. A weary man that has seen much in his long days, but is still simple and humble. He is no wiser than even the Little Crane.
As he thinks about it harder, the memories start to grow more vivid. He remembers the Devil King, he remembers the Toyotomi. He remembers the great battle that raged between the West and the East. He remembers the individual faces that he had snuck glances at from behind his sword.
They make him feel sad.
He has seen so much. Everything has changed. His rival has changed, the words have changed, the emotion shining upon faces has all changed. There is no consistent, except for the taste of sake. It makes him feel older than he could ever imagine. Never mind his beard of gray; never mind the scars that sew his muscles together. He is older than the sun and moon.
He smacks his lips as he twirls his bottle around in his large hands. He is a jaded old rock, contemplative against the sunset splashed sky. His time will be over soon. If there is such a thing as peace in these warring states, it is not his to achieve. He dreamed of it while he was young, but he has since forgotten. That is a job for a younger warrior. He remembers when the Cub of the Tiger of Kai staggered towards him, asking for advice, asking what to do in a time of such darkness.
Someday, the Cub will become a Tiger. He will take his place as the old guard, still rivaling with the One-Eyed Dragon. But by then they will just be two spiteful old men like he and Tadakatsu are now, growling yet grinning at one another as they watch the world and its scenes play out before them, linked in some sort of invisible understanding that only the old men have.
It will always be like that. As the world spins, the world ages. Its inhabitants blossom from children into capable adults, then slowly decay into elders and then finally shrink into dust. The Cub will shrivel, the One-Eyed Dragon will shrivel, the Sea Ogre and the Crane and the Crow and the Badger will shrivel. Their successors will shrivel.
But the Beast is to shrivel before them all.
Shimazu huffs out a breath, wiping the sweat forming on his white brow. It is too depressing to think of such things. He may be older than dirt, but he still doesn't know when he will die. It could be tomorrow, it could be another century. Life still dances through his veins in rhythm to his heart. If one has that rhythm, then they can continue to live life to its fullest despite their age in years.
He smiles to himself, his wrinkles crinkling his tanned face. He lifts his bottle up to his mouth and drinks – drinks until all thoughts of philosophy and death and hope and fear and battle are gone, and all that's left is a hazy mess of bliss.
Even so, he can't help but notice that the sake tastes the tiniest bit bittersweet.