Natsukashikute, chotto yotte-mita-n-desu. (I was feeling nostalgic, so thought I'd drop by for a bit.)

Situation 1: Mr. Tian rings the doorbell of Mrs. Mori's house, who is his old landlady.

森: まあ、ティエンさん、うれしいこと!とつぜん、どうしたの?