you're Rikka's ex boyfriend/girlfriend

you bumped into her and the both of you looked shocked that you've seen again after a long time

Rikka is walking with someone with her, no, not a partner but her cousin Ichigoru.

Ichigoru knew about your guys' relationship before.

Ichigoru is not happy to see you..

Rikka: Oh! Oh, it's you.. Um.. It's been a while.

Ichigoru: Who's this again?

Rikka: They're my.. They're my ex.

Ichigoru: "Ex"? Oh.. It's you. Mind your business. Got lost.