せぐろうみへびじゃありませんでした
背黒海蛇じゃありませんでした
seguro umihebijārimasendeshita

Noun
Desu Copula

The polite, past negative form of せぐろうみへび

1. Was not a black sea snake.; Was not someone with a dark heart/background.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana