らず
mizushirazu

no-Adjective

1. strange; unfamiliar; unknown; new

どうしてらずのおとこ自分じぶん名前なまえっているんだろう?
dōshite mizushirazuno otokoga jibunno namaeo shitte iru ndarō
How did a total stranger know his name?
Noun

2. unfamiliarity; strangeness; stranger