You hear a song from high school days, or run across a photo from a family vacation, and think about how nice those times were. You and friends are reminiscing and someone at the table brings up an incident you haven’t thought about in years. Someone crosses your mind, someone you once loved and who loved you right back. You revisit this or that town — where you previously lived, or went to college, or once enjoyed with someone special — and remember . . . “Ah. . . natsukashii . . .”