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've never seen such a bitter 
look on your face, Great Rimuru.
لم يسبق أن رأيتُ نظرة مريرة كهذه
في وجهك يا ريمورو-ساما
Ich habe Sie noch nie so wütend
gesehen, Meister Rimuru.
Nunca lo vi tan resentido,
señor Rimuru.
Nunca lo había visto tan resentido,
señor Rimuru.
Je ne vous avais jamais vu
l’air aussi amer, maître Limule.
Sembrate stranamente di cattivo umore, Grande Limur.
Está fazendo uma expressão de amargura
que nunca vi, Rimuru-sama.
А что вы вдруг грустный такой стали,
Великий Римуру?