It was the morning of December and Chuuya was walking to the agency to meet Dazai, he just so happens to walk pass by a shop that sells some good wine and couldn't resist buying some and thought he would buy some bandages for Dazai sience he noticed that they are getting old but once his feet reach the outside of the agency, Chuuya smile faded to a face of unamused... The entire building of the agency was covered in Christmas themed things... Light decorations, little dolls and glowing stars, Chuuya could only think of 1 person who is insane enough to pull off this stunt on the whole building... And his predictions were correct as he walks into the office of the agency where light decorations is everywhere with candy canes, chrismas tree  in the centre of the office with a star already glowing brightly on top, Kunikida is wrapped up in present wrapping, he is struggling to set himself free, Ranpo is indulging himself in Christmas sweets and junkfood while Dazai... Is picking out more Christmas decorations... Atsushi is trying to stop him and telling him that the agency already has enough decorations but Dazai was still not listening

Chuuya: *sigh* he's that excited for Christmas huh?
Atsushi: y-yeah... I was surprised when I saw him so pumped up... This is the most work he has ever done in the agency ever
Chuuya: ehhh I get it he loves Christmas... Alot. Ugh... Just like that 1 time back at the mafia he covered the entire building in decorations and even turned the boss into a Christmas tree... The electric bills were more then we could pay that month...
Atsushi: ehehehehe...
Dazai: Chibiko your here!! C'mon let's put up some decorations! Maybe we can turn Mori into a Christmas tree again! Or wrap him up in lights to put on top of a Christmas tree?!
Chuuya: no, we're not doing that, isn't it a little too early for decorations?
Dazai: who cares? I got everyone presents! I got Kunikida a meeting with his favourite author while his mission is in 1 hour~ I got Atsushi cat toys
Atsushi: I'm not a cat!
Dazai: I got Ranpo san his favourite Chrismas junk food oh and~ here's yours!

Dazai handed Chuuya a present box, Chuuya feels sceptical to open it but decided to anyway sience he knew Dazai will bag him into opening it, Chuuya opens the box to see a... Oddly big summer hat with a photo of Dazai that has a bow attached to it

Chuuya: a hat?
Dazai: yeah it looks waaaaaay better then that ugly thing you got on your head so I got it for you! There's a Christmas hat under it too hehehehe
Chuuya: my hat is not ugly and how is a summer hat looks better than it?! It's winter!! I'm not wearing a God danm summer hat!!
Dazai: awww Chibiko is so mean~ I spent so many hours picking that hat for you!
Chuuya: ah quit it with the waterworks act Im not buying it, ugh whatever I got you this anyway so you might as well keep it
Dazai: hmmm~?

Dazai opens 1 eye from his dramatic reaction pose and see Chuuya throw something towards him, he catches it and sees that it's a brand-new bandage for him, Dazai jumps over to Chuuya happily hugging him and taking a look at the bandage

Dazai: yaaay! The slug loves me after all! I knew you- uh...
Atsushi: w-wha... What's with that face...?
Dazai: what is this?
Chuuya: your brand new bandages
Dazai: yeah but why does it say "fish" all over it?!
Chuuya: because you stink like fish!! Didn't I told you to use shampoo when you bathe?!
Dazai: hey I'm a busy guy!! I can shower without shampoo whenever I like!!
Atsushi: uhhh... Guys please don't...

Atsushi stands in the middle watching the 2 began to bicker with each other like silly little kids as he set Kunikida free from the present wrapping while Kyoka was drinking milk

Atsushi: they are never going to quit arguing with each other huh...?
Kyoka: no... But that what makes their dynamic unique... Like you and Akutagawa
Atsushi: what?! Hey don't put me up with that guy!! C'mon all he ever does is come here and pick fights with me and chops my leg off, regeneration is not as easy as it looks... Plus it hurts every time...
Kyoka: what do you think he does with that chopped off leg he got from you?
Atsushi: I don't know something creepy like feed it to some pet shark that the mafia has? Ugh... Or worse... Feed it to his ability...
Kyoka: probably the second one... The mafia has no pet sharks...
Atsushi: oh...

A little bonus

Ranpo: hey Poe~! Merry Christmas!
Poe: ahh! Ranpo! What are you doing here?! Its the beginning of December!
Ranpo: ah who cares! You got that book ready? I got something special for you!
Poe: I'm just finishing the last chapter... But what is it that you got...? 
Ranpo: here look! I got you a racoon onesie! Doesn't it looks like Karl? And it's your height too! I got myself 1 too but it's not racoon tho...
Poe: o-oh thank you... You didn't have t-
Ranpo: oh I saw these little scarfs and mittens for cats for sale I bought some for the president's pet cat and I even bought some for Karl! Here try it!

Poe face turn bright red as he sees Ranpo already preparing presents for him AND Karl, he watches as Ranpo tries to put the little mittens on Karl hands and wrapped the little scarf around his neck... Karl seems to like it and jumps on Ranpo head and sleeps

Ranpo: look he likes it
Poe: can we skip to marriage already?
Poe pov: I'm glad he likes it
Ranpo: your thoughts switch with your words didn't it?