Satoru has left girls swooning after his first kendo practice.  Everyone is talking about him, and there's a clamor when they discover that he's living with Makoto.  But at home, his stiff demeanor makes it very awkward.
You have no idea!
Du hast ja keine Ahnung!
¡Si no sabes nada!
¡Si no sabes nada!
Tu comprends 
rien à rien.
Tu non sai un bel niente!
Você não sabe de nada!