What the Heck, Let's Give It a Shot (2)

I returned home first.

Or let me go without a fuss, too.

There was a good reason for that.

[—Oppa, tell me before you go anywhere, and come back! Promise!]

[—I… no, Oppa's sorry. I won't go anywhere without Serin from now on.]

…It was a promise we'd made around the time I was adopted.

I had to keep this one, absolutely.

"Serin, Oppa's going to Floor 6."

"Hweeeek!? Why all of a sudden first thing in the morning!? You just cleared Floor 5 yesterday!!"

"It's good to climb quickly."...