いたずらじゃありません
悪戯じゃありません
itazurajārimasen

Noun
Desu Copula
na-Adjective
Negation Auxiliary

The polite negative form of いたずら

1. It's not a prank.; It's no joke.; It's not mischief.

Negative
Polite
Terminal Form
Usually Written in Kana