弟切 おとぎり そうじゃありません
otogirisōjārimasen

Noun
Desu Copula
Negation Auxiliary

The polite negative form of 弟切草

1. It is not younger brother cutting grass.; I am not cutting grass like a younger brother. ; (Implies: I am not inexperienced/naive.)

Negative
Polite
Terminal Form