EDIT (15/01): Fixed a mistake.
Kashuu's daily routine is the same every day.
He wakes up, washes up and makes his preparations for the day. 'Preparations' involve an entire hour dedicated to lining his eyes, painting his lips and touching up his red nail polish, then dressing up with perfect kosode bows or precise scarf knots.
Once he is done, he will wake Yasusada up. It's a tedious, no-reward job that demands more effort than the amount he puts into himself. Kashuu is already dragging the half-asleep sword spirit around and helping him prepare and is still bewildered that Yasusada can barely come out decent looking. His hair is never not out of place or some strange stain is always finding its way onto his scarf. While Yasusada is still half-living in slumberland, it's Kashuu who takes a brush to his hair to tame it or gets a wet cloth to dab out the worst of the stains.
But for the few days, he hasn't had to go through this part of his morning.
Kashuu reaches for the eyeliner pen and the back of his knuckles brush again the stack of letters, edges aligned neatly with the table corner. There's 3 in total, one for each day Yasusada wasn't there. The first one was the earliest and thickest, filled with pointless drivel like what food he ate from which store in which street of Kyoto. As they got more recent, they became thinner, with the last one a single sheet containing a straight-to-the-point report about Yasusada's training.
Kashuu isn't worried. (Yes he is.)
Although the "tug at the heart" urge to revisit the past hasn't pulled at him, he knows what Kiwame training means. It's a trail of self-discovery and coming to terms with inner demons. Everyone would come back somewhat different and it wasn't just fancier clothes. Other swords like Namazuo and Sayo had returned significantly happier than their past monotone selves.
He knows its what Yasusada is also going through. And yet, the content of the letters worry him.
Because it's Yasusada. Yasusada, who sneaks extra carrots to Hanataro the horse even though he gets yelled at by Hasebe every time. Yasusada, who talks to the plants so they will "grow up happy and healthy". Yasusada, who bombards a letter with insignificant details and doesn't mince longwinded letters about a funny-looking bird he saw for straightforward reports covering the bare minimum of what he did that day.
The other Shinsengumi swords have told him not to worry. Aside from him, they have all gone on their own journeys and come back different. He wants to believe them, because obviously they know about Kiwame journeys better than him. But he also knows Yasusada better than them, better than anyone else. The letters he's receiving should probably be a cause for concern.
Kashuu clicks his tongue. He hadn't been paying attention and had drawn a squiggly line, an amateur mistake. He grabs a tissue and wipes, but it refuses to come off.
Eventually, he gives up. He gets up and takes the short stroll to the citadel mailbox, a habit acquired after Yasusada left. But strangely, there's no mail in it when he checks. Then he remembers that today is the fourth day and Yasusada should be arriving back anytime soon.
Hopefully he does. Because Kashuu is not beyond picking up his weapon and combing all five final years of the Bakumatsu period to look for his troublesome friend.
And that's when he hears it.
"I have returned."
He whips around. And runs.
He doesn't care how he looks. He doesn't care that his kosode knot looks like a child's attempt at shoelaces and his eyeliner is actually a jellyfish tentacle. Yasusada is back and that's all that matters-
Kashuu stops.
He doesn't recognise the boy in front of him.
Not in a good way.
In a bad way.
The long-haired boy with sky-blue eyes stares back at him. His hair is loose, adorned with only a familiar white headband. He's wearing a white yukata under his Shinsengumi haori, nothing else. Not even armour. Kashuu has never seen this look because he was long gone before it happened, but he's heard enough to know.
"Okita...?"
The boy blinks.
"It's me, Kiyomitsu." He answers. In a tone not devoid of emotion, but a tone that sounds entirely un-Yasusada-like and entirely wrong.
No. This isn't right.
He thinks he feels sick.
This isn't-
"-Yasusada." Kashuu says at last. Yasusada nods. It takes Kashuu every last bit of him that isn't in incoherent, non-functional shock to dredge up a smile. "You look great. Welcome back. Oh, um, you should probably report to the master first."
"That's right. See you later." Without a wave or a smile, Yasusada turns and gets moving. Kashuu waits until he rounds the corner.
Then he crouches and lets the tears run down his face.
A/N: Aka the reason I'm afraid of sending Yasusada for Kiwame.
Notes:
The letters Yasusada sends to Kashuu aren't the same as the ones he sends to the Saniwa (the ones on the wikia if you read it).