As Asta and the others were chasing the creature that lived in the cave beneath the Yultim Volcano Trail, they happened upon a dungeon. They were then ordered to explore the dungeon by the royal capital, so they split into groups and went in. They head in with Leopold and Vice Captain Randall, but those two end up running into the creature from earlier. They work together but cannot defeat the monster, which makes Leopold feel useless. At that moment, Leopold remembers the strange feeling he felt when he was fighting the elves, and...
So that's why Captain Fuegoleon 
and Lady Mereoleona
لهذا السبب دعا القائد فويغوليون وميريوليونا-ساما
Ordensführer Fuegoleon
und Fürstin Mereoleona
Por eso el capitán y la señora
Mereoleona trajeron a los Toros Negros.
Por eso el capitán
y la señora Mereoleona
C’est pour cela
que Fuegoleon et Mereoleona
Ecco perché il comandante Fuegoleon 
e la nobile Mereoleona
É por isso que o Capitão
Fuegoleon e a Mereoleona-sama
Так вот для чего капитан Фуэголеон
и госпожа Мереолеона позвали «Быков».