Rimuru decides to throw a summer festival resembling the ones held in Japan. The monsters have never experienced a summer festival, but when they hear that it's a party, they go all-in to prepare. All the monsters of Tempest work together and eventually come up with masks, paper lanterns, and even festival floats. On the day of the festival, everyone in the town enjoys piping hot takoyaki, cold shaved ice, yukata, and a Bon dance. In the end, they fill the skies with fireworks as the festival reaches its climax...
Master gave us the challenge of 
putting on this "summer festival."
منحنا مولايّ تحدّي تقديم مهرجان الصّيف هذا
Das Sommerfest, das mein Herr
für uns veranstalten ließ, …
El amo propuso
que celebráramos este festival.
El amo propuso
que celebráramos este festival.
Ce festival d’été
est une idée de mon maître.
Il mio padrone ha proposto di fare questo festival estivo.
Meu mestre nos deu o desafio
de montar este "festival de verão".
Хозяин отдал сложную задачу —
провести фестиваль.