いたずらじゃないです
悪戯じゃないです
itazurajanaidesu

Noun
Desu Copula
na-Adjective
Negation Auxiliary

The polite negative form of いたずら

1. It's not a prank.; It's not mischief.; It's not teasing.

Negative
Polite
Casual Register
Usually Written in Kana