The boy who Hayate meets is revealed to be Wataru Tachibana, Nagi's fiancé. However, Nagi and Wataru can't stand each other.
You see, you shouldn't yell 
in underground spaces like this.
Bueno, no debería gritar en 
sitios subterráneos como este.
É que nunca se deve fazer barulhos
altos no subsolo.