かさがいじゃなかったです
笠貝じゃなかったです
kasagaijanakattadesu

Noun
Desu Copula

The polite, past negative form of かさがい

1. Wasn't a Kasai shell.; Wasn't a shell of the Kasai family.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana