It's been five days since Saitama became a professional hero and he has yet to do anything heroic. When Genos informs him that C-class heroes who don't fight bad guys are dropped from the hero registry after a week of inaction...
That's the mystery.
.هذا هو الغامض في الأمر
Das bleibt ein Rätsel.
C’est là tout le mystère.
È un enigma.
Ci sono varie teorie sulle cause...