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.
I hate to burst your bubble, but...
...أكره أن أخيّب أملكِ، لكن
Es tut mir, leid dir das zu sagen,
wo du dich so freust,
No quiero aguarte la fiesta,
No quiero aguarte la fiesta,
navré de refroidir
ton enthousiasme,
Mi dispiace distruggerti il bel momento,
É difícil dizer isso quando
está tão feliz, mas...
Мне очень не хочется тебя расстраивать…