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Prologue

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"promise me, brother… no lie and no secret between us".

That's simple promise that they have made when they're only children.

And here, on the Cosmos garden where they're always spending time together when Hak tells her that he will go to Hiryuu Castle as Yona's bodyguard, she is frowning like she will cry whenever she wants and he has prepared himself. She doesn't cry instead she is angry. She is only 14 years old, yet she's looked more mature than her true age when she reaches out her hand to him after knowing he will go, her tears threatens to fall yet her eyes holding back her tears with such passionate on her looks.

"promise me, Hak… between the two of us, whoever will survive and life longer than other who passed away first, must stay alive, continue their life to protect their precious thing, to find their happiness and their reason to keep alive, live a life happily so the one who has gone first won't have any regret to leave this world before the other".

"sounds like someone will die before me, I hate this kind of promise because it sounds like one of us will die very soon", Hak narrows his eyes curiously "why are you asking me to make promise like that, Setsuna?".

"Hak", Setsuna calls him with demand tone "promise me?".

Alright, Hak has no choice but grabs her hand "…I promise".

There's no way he will forget that time, that night he just wants to go back to his room after he has decided to stay at Hiryuu Castle to accompany princess and not going back to the capitol Fuuga, his hometown (he knows Setsuna and Tae Yeon, his sister will be mad and brother will be disappointed, but hell yeah, he does choose to stay with Yona instead).

He won't be mistaken by what he has seen, he finds Setsuna's unique hair and follows her, sneaking from Hiryuu Castle till they reach the hill where they are able to see Hiryuu Castle and Kuuto below the hill. Setsuna is standing right in front of him, scowling, scolding him for not fulfill his promise to come home, back to Fuuga frequently or at least when the New Year's vacation if he's that busy. What's more, he is supposed to go home on this New Year's vacation, considering King Il has given the permission for him to come home.

With tears streaming down her face, she scolds him "don't make a promise that you can't fulfill, you moron?!".

Right, before he's installed as Wind Tribe's General and lived on Hiryuu Castle as Yona's private bodyguard, on that Cosmos garden at one of Fuuga's mountain when he has told her about that, after they have made that promise, she has cried a lot. Of course, without no one tell her, she has known about it already but she is waiting for him to tell her with his own mouth. Typical of Setsuna, she is always like that.

Guilt surging within his heart when he sees her cry in front of him "Setsuna, forgive me, I—".

"I'll always be waiting for you, Hak… that's what I told you before, right?", Setsuna smiles in the midst of her tears with the slight of bitterness "but in case this is the last time I see you, I will tell you… about all of those promises we have made due to my selfish reason… I want you to promise important thing as well…".

After she reaches out to him, doing something unpredictable that make his eyes widened.

After let single tears that makes a wet line on her cheeks, whispering sorry and good bye.

He startles when a pair of wings appears from Setsuna's back before her figure vanishes in the thin air and changes into spreading beautiful snow as she whispers one last thing, the most important thing that he will never able to forget about her.

He wanders, looking around for her and calling her name, screaming her name till he is only able to stay still. He thinks this is must be only a dream, so he is going back to Hiryuu Castle and fast sleep. Only to find Mundok tells about Setsuna's death on the morning.

Mundok tells him that her funeral will be held after the New Year's Ceremony on Hiryuu Castle and he wants to pick him up to come home but Hak refuses to come back. He refuses to believe it, yelling to Mundok that he will only believe if he witnesses her death right in front of his eyes which make Mundok pulls him into the bear hug and whispers to his ear to receive the fact when Hak yells her name like he has done last night.

"SETSUNA?!".

It hurts. It hurts as if half of his heart, himself that always stay by his side since they were born into this world has gone. As if his heart wants to die right away but he has promised her, so he has no choice but fulfill his promise. He wonders, does this mean she has known that she will die soon when he isn't there around her, that he doesn't near her which make her ask him to promise?

Hak jolts from his bed, wide awake. He snickers as he running his hand on his hair, revealing his sapphire eyes.

"Dream? Huh, what was that? Does it because my conversation with the princess yesterday?".

Everything about the princess always stresses him out, and if her sister is still alive, he's sure she can make a tag team with the princess as 'tag team of woman who can stressing him out'. Really, those two are… enough, hasn't he decided to fulfill his promise to his little sister? Countless time he has convinced himself to let her go, to bury his childish that hope she is still alive, keep telling to himself that she has died and the one who met him that night is her spirit. But after that dream, he wonders if there's the part of his heart that hasn't let her go till now?

"promise me, Hak… never ever let go of those precious to you".

"I've been thinking, when the time comes that I'll be fine even when you're not around, I'd give you back your freedom".

"one has asked me to not let go and one has intended to let go of me, huh? If you'd let me go in the end, princess, then it was no use for me to leave her…", Hak huffs heavily and lifts his head, looking to the clear blue sky today "Setsuna… I wonder if you're smiling or laughing at me right now above the sky? When will I see you again?".

"you can see me right away, you know?".

Too shocked by what he has seen, Hak drops Tsu Quan Dao on his hand to the ground, his face turns into wonder and surprise "…Setsuna?".

She approaches and hugs him, cupping his face with sweet smile on her face "I missed you so much, Hak Onii-sama…".

Hak envelops her on his bear hug before caressing her face "is this real? Am I dreaming? Or is this the afterlife?".

She grabs the hem of his robe and pulls his face down before hugging him and digging her finger on his back "this is real or not, just proves it… with your feeling…".

Hak frowns and breaks the hug, grabbing her shoulder "…who are you?".

Hak realizes she isn't Setsuna that he knew, so he asks him to stop imitate her and reveal her disguise. She introduces herself as Tsurara, Setsuna's older sister, her half-sister because they have the same biological father.

"what do you mean? Setsuna had…".

"silly, she is still alive, looks like she doesn't believe you at all, that's why she never contacts you, even just for telling you that she's still alive?".

That's when troops with armor and complete weapon who riding horse come into them, their leader comes to the front "we mind if you keep wandering around as you please, princess…".

Hak doesn't understand at all, why their leader acts like he's just witnessed a ghost and his face turns pale when he looks at him.

"you are still alive?! no, even if he is still alive, he is supposed to be older…", sly smirk appears on his face when he gets back his confident "ah, I see… must be her child, what a lucky…".

Everything become confusing matter for Hak because the leader of the troops, this old man claims that the Emperor will be pleased if they bring Hak's head, the son of traitor. He also mentions about how that lion-hearted Snow Queen will react if she knows what happen. Of course, Hak won't let them chop his head off without he knows the reason for. He fights back but he is quite in a pickle because he's outnumbered.

Like that night, he's in vulnerable state as he laying on the ground with several soldiers pointing their spears to his neck while that woman, so-called as 'princess Tsurara' tying his arms with chain and touching her knife to his throat.

"don't move, I only help to bring you to meet with someone".

When he meets 'someone' that she means, and he knows what they want, his heart lurching as if its will fly out of its place, palpitating in fear "no?! princess, Yun and Dragons, run?!".