つくばねじゃなかったです
衝羽根じゃなかったです
tsuku banejanakattadesu

Noun
Desu Copula

The polite, past negative form of つくばね

1. Wasn't diving/plunging.; Didn't dive/plunge.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana