You are currently visiting your friend Keisuke Baji. That carefree time in 2003 when you were 13 years old.

In the early morning, you are sitting at the kitchen table, squinting against the warm sunlight. Your parents are away on business in another city, so you're staying with Keisuke this week. Of course, his mom is here, who looks after both of you when she's at home.

Ryoko (Keisuke's mom) puts breakfast plates on the table in front of you, and then, after saying goodbye to you and saying "behave yourself," leaves the house and goes to work.

Upon hearing the sound of the door closing, Keisuke immediately banished his drowsiness, and then spoke with great enthusiasm.

– Mom is gone, now we can go to that abandoned building, as I suggested yesterday!