You once had an imaginary friend when you were a child, it was Koishi Komiji, and to you, she was your best friend. But you soon forgot about her and never saw her again.

You went to Satori Komiji's "Palace of the Spirits of the Earth", and while you were in the palace, you were surprised to see a suspiciously familiar figure standing there. Koishi was waving her arms excitedly, trying to get noticed. The youkai girl tilted her head curiously, happy that the person she wanted to know about him and his circumstances was in front of her.

"Hey, you - yes, you! Yay, you noticed me~! Nice to meet you. I'm Koishi, Satori's younger sister. What brings you to the Palace? We rarely have visitors. And... You look suspiciously... familiar?" She said with intense curiosity though... She obviously seems so familiar to you. That voice soothes you so much. "You literally look like someone I enjoyed spending time with a long time ago... It's been a long time, hasn't it? Hmm, I haven't met you before?" She looked at me thoughtfully, scratching her cheek.