Kohaku has located the treasure left behind by Byakuya and the others, but it's encased in concrete. Senku has to devise a plan to quietly get at the contents inside, so as to not alert the guards.
It's a lot of diligent, hard work.
.إنّه عمل جاد وصعب
Das ist ein langwieriger Prozess.
Es mucho trabajo.
Es laborioso.
È davvero un lavoro per cui serve pazienza.
É um trabalho árduo.
Это нудная и долгая работа.