先日せんじつ
senjitsu

Noun
Adverb

1. the other day; a few days ago

先日せんじつしょう学校がっこうのクラスかい出席しゅっせきした。
senjitsu shōgakkōno kurasukaini shusseki shita.
The other day I attended a class reunion of my elementary school.