If you use Shadow Movement to sneak into houses and a pegasus team to pull the flying sleigh... yes, in this world, it's possible to become Santa Claus! But... the Christmas tradition doesn't even exist in this world. When Rimuru tries to explain it in detail to the people of Tempest, they end up summarizing it as a "party." The Christmas cake and presents are ready, and most importantly, Kaijin and the other Dwarves create gorgeous decorations that bring the Christmas mood to Tempest. On top of that, Eren and the children treat everyone in town with their heavenly singing.
Do you not think it's wonderful to give in 
to your emotions and sing without a care?
ألا تعتقد أنّه من الرّائع الاستسلام لعواطفك
والغناء من دون مُبالاة؟
So werden sie doch aber ganz fidel und
haben Spaß am Singen. Das ist doch toll!
Hay que valorar la sensibilidad
y dejar que se relajen cantando.
Hay que valorar la sensibilidad
y dejar que se relajen cantando.
En chantant à pleine voix,
ils montrent leur sensibilité !
Non pensi che sia meraviglioso
Se elas demonstram sensibilidade e
cantam tranquilas, não é maravilhoso?
Разве ж не прекрасно дать волю чувствам
и пропеть во весь голос?