The demon's apprentice

Odd

If you'd ask Kokushibo if he cared about Tanjirou, he'd not answer. He'd stay quiet, because at this point, he doesn't know either. Tanjirou is just a demon he's teaching, so he shouldn't care about him. Yet, when the boy growled and tried to hide behind him, Kokushibo couldn't help but bring the boy into some kind of hug-like hold. God, is he going insane? Though he probably is already insane.

The boar headed demon slayer doesn't seem fond of Kokushibo's action. Even with the lifeless head covering his face, Kokushibo can still sense the anger.

"Let go of Monjiro!" The boy yells and almost runs to Kokushibo, but is stopped by the wind hashira.

"Are you an idiot?!" The hashira yells.

"Is this... boy prehaps... Tanjirou's old friend...?" Kokushibo thinks. Well, from the way he seems to react to anything that happens to Tanjirou, it seems yes.

Kokushibo looks down at Tanjirou, to see if seeing his old friend reminded him of his human life. But Tanjirou is only glaring at the demon slayer, like an angry pitiful child. Maybe his sister would've reminded him, if she were still alive that is.

But Kokushibo is no fool. He knows that even a demon who has lost their human memories long long time ago, can remember when seeing someone they were close to. And Tanjirou has only been a demon for about a year now. Why doesn't his friend remind him?

The answer is simple. Because Kokushibo is able to give something to Tanjirou that he has been wanting for years now. It's stupid, but it makes sense.

Kokushibo heard that Tanjirou was around thirteen years old when his family was slaughtered by Muzan and his sister turned into a demon. Even though he wasn't a little kid anymore, the trauma did a number on him. The way Kokushibo has been treating Tanjirou for the past month, is almost family type of. The uppermoon isn't so harsh on the boy during their training sessions, and even gives him compliments when the boy succeeds. Heck he even helps Tanjirou do his hair!

Ever since Tanjirou's family was killed, something inside of him made him cling to his sister, the last remaining bit of his family. But now when she was gone as well, Tanjirou had nobody. Nobody but his sensei, Kokushibo, who seemed to care for him.

The small childish part inside Tanjirou's still developing brain, yearns for a family-like relationship. And who has been there for him the longest he can remember? Kokushibo. Who has trained him so he'll get stronger? Kokushibo. To him, Kokushibo is the only one who hasn't abandoned him yet, and he clings to that tiny bit of hope, that once this night is over, everything will go back to normal.

The stone hashira prepares to attack, and Kokushibo can feel Tanjirou's hand tighten around the fabric of his kimono. Then he loosens complitely.

Don't die, sensei.

Kokushibo can't help but comfortingly pat the boy's back.

I won't, do not worry.

Then Tanjirou retreats and takes his sword out. Even though he looks determined, if you look hard enough, you can see the amount of nervousness the boy is hiding. He hasn't been up against a real opponent yet. He's afraid. Afraid that he'll die. Afraid that Kokushibo will die. He glances at Kokushibo whose stare is blank as always, but Tanjurou somehow finds comfort in it.

"It'll be alright, Kokushibo-sensei is strong." He reassures himself. "He personally trained me and he believes that I am strong enough."

Tanjirou takes a deeb breath, and attacks.