Isaac and the Black Sword Knights are responsible for training the Maihama army. While he's in Maihama Isaac gets to know the new crown prince of Maihama, a young boy named Iselus.  Iselus respect looks up to Isaac and respects him.
At a party for the crown prince's birthday, assassin's make an attempt on his life.
Well, this is what happens when I get serious.
Bueno, esto es lo que 
pasa cuando voy en serio.
C’est un jeu d’enfant
pour quelqu’un de ma trempe.
Beh, ecco cosa succede
 quando mi impegno seriamente.
Bem, é isso que acontece 
quando eu levo algo a sério.
Я же тут не в игрушки играю!