reminiscence; nostalgia; fond memories of the past
A somewhat literary or formal word for fondly recalling the past. In everyday speech, 懐かしさ or 思い出 are more common.
His story was filled with a sense of nostalgia.
I looked at old photos, indulging in feelings of reminiscence.
reminiscences; talking about old times
From 懐 (かい, 'to cherish, to think fondly of') and 旧 (きゅう, 'old times, the past'). The combination conveys cherishing memories of the past.