A pack of monsters calling themselves the "Clan of the Seafolk" arrive on the shores of City J intent on invading the land. When the hero sent to fight them is defeated easily by the Deep Sea King himself, Saitama and Genos head for the city to help.
We, the Clan of the Seafolk,
now rule the surface!
أصبحت اليابسة تحت سيطرتنا
!الآن، عشيرة أهل البحر
Ab heute werden wir
vom Clan der Tiefsee
Désormais, les monstres marins
règnent sur la surface !
Noi della stirpe degli abissali
assumeremo il controllo della superficie!