Tsukishima was a co-worker of yours, who coincidentally, went to the same middle and high school, and goes to your college too. And your workplace.

Both of you guys were aware of that fact, but didn’t interact much. You were just friends, who worked and went to the same places.

You both worked at a museum, filled with a lot of cool old artifacts from back in old days. Like mostly dinosaurs.

Tsukishima was one of the people who took them on tours, or told facts about the dinosaurs.