Luna and Yuna are biological twin sisters or I might say psycho sister. They both don't have any fear but one fear they both had was of being 21 year old. Basically there step parents were poor at the time when they were adopted . So, to become rich they made a deal with the devil kingdom's king. The Deal was that - Luna and Yuna  have to marry there both son's when they become  of 21 year old. When Luna and Yuna was of 10 years there parents died in a car accident. Because of loneliness and the fear they both became cold and transformed into the moon psycho killer sisters - Lunar and Yunar .

Present

Both Luna and Yuna is now of twenty years and they soon will become twenty one as tomorrow is there birthday. They both were just at home eating snacks, but suddenly the doorbell rings. Luna goes and open the door , she found a letter on the floor so she picked it up. The letter was strange , it was written by a red thick liquid which they can recognise it was blood as they had killed so  many people. One more thing they found strange is that there was no address from where the letter came and who gave it. In the letter it was written about the deal and saying that they don't have to pack there things. They both were confused about what deal it was written about as they forgot about the deal , but after some time they slept and wake up in the morning. After doing the morning routine , they started to clean there house but Luna felt like someone is in  their house.

Luna: Yuna i think there is someone in our house ...... Yuna: oh...

Saying this Yuna grabbed a knife and then they both started to move towards the living room and as they entered there they are shocked  by seeing who are they......They were surprised and shocked to see some people in there living room, they were there friends.

Lisa: Happy Birthday to both of you !!!!                       

Jennie: Now you both are gonna be of 21 years.           

Both Luna and Yuna : What today is our birthday.         

Jisso : Yes.                                                                            

Both Luna and Yuna : ohh.... Ok then lets party..

They all do fun and enjoy the whole day but at nearly 12 o' clock , there friends left and also Luna and Yuna felt like sleepy so they goes to home they reached home at correct 12 o' clock and just when they were going to lie down on the bed the electricity gone and all security camera turned off.

Luna: Today i think we also cut a hand of thief like we   cutted the cake .

Yuna: Yes, I can bet, tomorrows news headline will be - " One more haunt by Moon sisters."

It was all dark in there room and suddenly a portal appears

Yuna: what the f*ck!!

Luna: Mind your words in front of me...

Yuna: Ok-ok, but what the Hell is this?!!

Luna: maybe it is some kind of a portal...

Yuna : So can we go inside this?

Yuna was just going inside the portal but suddenly some people came out from it.

Yuna: Who are you people?? And from where you came?? (shocked and confused)

Guard1:We are the guards from the devil kingdom.. Our kings sent us to bring you both to the devil kingdom and maybe our kings also sent  you a letter.

Luna: The letter written by blood?

Guard1:yes..

Yuna: And what if we say that we don't want to go?(smirk)

Yuna and luna refused to go so they just do some magic on both of them and make both of them asleep....but before they did that yuna and luna hides knife with them.

Guard1: lets go..

After one hour they both wakes up and find themselves in a strange but beautiful place. It was the forest of magic. The guards are talking about something and without wasting time yuna and luna killed them..

Luna: I didn't thought that it will be that much easy to kill these brats..

Yuna : Comparing them with the people we killed it was a piece of cake. 

Luna : Now we have to find the way to get out from here.. 

They are  just discovering the place but suddenly a old man appeares ..

Old man : Little kids , what are you doing here in this devil kingdom?, i think that you both are humans then why are you here??

Luna : And why should we tell you this ? You ugly old man..( while holding the knife)

Yuna : Sister if you are tired then let me do this for you..

Old man : sure you can kill me you don't want to know how to get out of this place..

Yuna: sis just kill him he is getting on my nerves...

Old man: if you complete my tas...k.( luna just cuts the old mans neck)

Yuna : Sure but its too late, now me and my sister are tooooo tired...(teasing)

When they both were leaving, they heard a roar  which make them to turn around and they saw that the old man is became a furious beast.

Yuna: how could it be possible!!!!!

Luna: everything is possible in this devil kingdom..

Yuna: so, now what we have to do?

Luna: asking as if you don't know..(smirk) just kill this beast!!

Yuna and Luna tried there best to kill the beast but the beast is very powerful but then suddenly two person come flying ....the two kings.

Luna: watch out Yuna!!!!!!!

A big stone is just going to hit Yuna but someone saved her........

Taehyung: are you ok??

Yuna : yes but who are you??

Jimin: tae its not the time of tea party!!!

Taehyung: may be we should talk after this...

The both kings started to fight but because of losing half powers they also couldn't kill the beast..but suddenly the necklace of luna and yuna that is given by there real mom started to shine and both luna and yuna started to fly and there eyes become red and a red aura appeared and some how they killed the beast with there powers till the kings recovered. After the sisters killed the beast they both becane unconscious and begin to fall but the devil kings catches them.

Taehyung: let's take them to our castle , hyung

Jimin : yes 

(reader : why the kings only have half of his powers ??

author: the previous king means their dad  already knows that his son's will also refuse to marry strangers so he does a magic through which when the girls will became of 21 his sons will lose there powers and when the girls  will became the queens of the devil kingdom and marry his sons that's when his son's will receive there powers)

Back to the story 

Soon the guards come 

Guard 1 :  your majesty sorry we are late but are you both ok ??

Taehyung: there is no need to say sorry and yes we both are ok...

Jimin : we have to go to castle

After some time

In castle the both sisters were in different room as luna is in jimin's room and yuna is in taehyung's room..

Luna was sleeping and jimin was patting her head..... slowly luna begins to wake up

Luna: ahh!... my head i couldn't remember anything.

Jimin: don't worry

Luna : who are you and where i  am ?

Jimin: i am jimin, the king of the devil kingdom and.. you are in my room.

Luna: where is my sister? Is she ok??

Jimin: yes yuna is totally fine and sleeping in my brother's room 

Luna: ahh !! My head!!

Jimin just hold her hand and luna started to see a purple aura with some purple butterflies 

Luna POV : what is happening to me and why i am seeing this purple aura just when he holds my hand??

Jimin : it's because you are mine

Luna: wait ,,, you can read my mind!!

Jimin : yes

Luna : and what do you mean by i am yours 

Jimin: it means you will be my queen and my wifee

Luna : but i don't want to marry you.....

Jimin:  you will..

After saying this he does some magic to make her sleep and left...

Outside the room.

Jimin : do you find out how she and her sister received powers ??

Priest : you said that after there necklace began to shine they received powers,  so it can be because of there necklace..

On the other hand , in taehyung's room

Yuna was also sleeping and taehyung was lying behind her ...

Yuna : i can't bear this pain... my head is spinning....!!!

Taehyung: don't worry, i am with you and you will be ok soon....

Saying this he holds her hand and yuna hugged him as she is feeling a quite good and then they both slept...

Meanwhile 

Priest : one more thing tomorrow is purple moon . You and luna is going to be very very very powerful.

Jimin : i will take care of it..

Jimin POV : let me check if luna is ok or not..

Jimin went to the room and led  down  in front of her and patted her head so she could  feel  nice and luna is feeling nice so she just hugged him and her necklace loosed out

Jimin: so this is the necklace..

On the necklace there was a symbol of devil kingdoms one of the powerful queen rosalin..

Jimin: no, this can't be happened is she and her sister is the daughter of aunt rosalin...  so this is why she become that much powerful..

Suddenly luna said

Luna: ah....

Jimin : don't worry love, it will be ok after sometime...

He also slept ..

Next day

Jimin wake up early as he has to do some other work before breakfast. Luna wake up after sometime...

Luna: ah. What is this strange feeling in my body?

She saw a note at the side table. Then she picked it up started to read:

In the note:- 

                     Good Morning my love, i wake up early because i have to do some other works before breakfast,, anyways i have leave a beautiful dress for you . After you got ready meet me in dinning room.... Jimin

Luna see the dress and it was beautiful. After doing her morning routine she got ready and goes outside the room, where two guards are standing...

Guard 1: Good Morning your highness(bowed)..

Luna: why are you saying me this ,, ok just leave it show me the way to dinning room.

One of the guard told her the way to dinning room and leaves.when she opens the door she finds that jimin is waiting for her while sitting...

Luna: Good Morning

Jimin: good morning love.. lets have breakfast

Luna: arrr... don't call me that. Well where is my sister ???

Jimin : yuna is sleeping in my brother's room with my brother .. you know na they both are sleepy head..

Luna: wait what they both sleep together in same room.(shocked) 

Jimin: yes, just like us.

Luna: forget it. First tell me why i am feeling this much strange??

Jimin: its just because of your powers .

Luna: Power! I Don't have any power....

Jimin: you do have from the time of our marrige deal but you didn't got the situation nor anyone told you about it it just hide inside you but when you got the situation when you killed the beast your power also wake up 

Luna : what!!! I killed a beast!!!!! I can't remember anything .......

Jimin: it is also because of your powers 

Luna : ohhhhh....

Jimin: yes and you have to be with me the whole day.

Luna: and why ???

Jimin: remember last night when i touched your hand ??

Luna: yes, when i saw a purple aura and also some butterflies , but you said it was because i have to marry you .

Jimin : yes it also means we will get very very very powerful on purple moon night that much powerful that we can kill or harm anyone even our close one..

Luna : oh.

Jimin: after doing the breakfast i will teach you how to control your powers..

Luna : ok but what about my sister??

Jimin: tae will take care of it .

Meanwhile 

In taehyung room

Yuna: ahh my head is still aching , wait where i am and who are you?????

Seeing taehyung lying in front of her she is just going to kick him but before she could taehyung wake up and stoped her kick.

Taehyung :  are you ok??

Yuna : i am ok but who are you???

Taehyung : i am taehyung the king of the devil kingdom and you are in my room sorry from now in our room...

Yuna just get up but due to weakness as her powers are still not awaken she is going to fell but taehyung holded her before she fall.

Taehyung: be careful.

Yuna : no worry its just -- just because my foot slipped...

Taehyung : oh i see well you have to be with me all day long and be away from your sister

Yuna : and why i have to follow your order??

Taehyung told her all the things and also about the moon 

Yuna : ok and what is our moon colour ??

Taehyung : pink moon which is after the next week 

Yuna : ok well i am so hungry

Taehyung : me too so ....lets go to the dinning room ..

They reached to the dinning room and hve ther break fast with everyone 

Luna : well i have to admit it, it was a sweet breakfast.....