Mumei and the others are thrilled with a sudden pool day. However, their joy turns to horror when shadowy figures appear in the water. Sharks with plans of world domination? How can this be? With no possible escape, how will Mumei and the others cheat their way out of this new challenging test?
But it's cruel to be shut up in your room 
studying when it's finally summer vacation.
لكن من القاسي أن تدرسوا وراء أبواب مغلقة
في غرفكم بينما حانت العطلة الصيفية
andererseits wäre es eine Schande, die Sommer-
ferien lernend auf dem Zimmer zu verbringen.
Pero es cruel pasar las vacaciones
de verano encerrados estudiando.
Pero es cruel pasar las vacaciones
de verano encerrados estudiando.
de passer tout l’été enfermé
dans une chambre à réviser.
Ma che peccato doversi chiudere in camera 
a studiare anche durante le vacanze estive!
Mas é cruel ficar fechado no seu quarto estudando
 quando finalmente estamos nas férias, né?