
After summer vacation, So-ri transfers to a new school and finds an anonymous letter in her desk drawer with an introduction to the school and a clue to finding the next letter. "If you want to keep reading, find my second letter!" While following the clues in the letters and searching all over the school like on a treasure hunt, So-ri keeps running into a same-aged student named Dong-soon. So-ri and Dong-soon quickly become friends as they search for the letters together. As she finds one letter after another, the special connection continues, and So-ri's curiosity grows for the mysterious sender. "I want to find the last letter and thank you in person."

Lee Soo-hyun
Lee So-ri (voice)

Kim Min-ju
Park Dong-soon (voice)

Min Seung-woo
Jung Ho-yeon (voice)
Nam Doh-hyeong
Ahn Seung-kyu (voice)

Kim Yeon-woo
Kim Ji-min (voice)
Lee Mi-na
Kim Sunny / Lee Su-kyung (voice)
Kim Chae-rin
Cho Ho-ran (voice)
Kim Yea-lim
Yang Song-hee (voice)

Kim A-rong
Young Lee So-ri (voice)
Lee Serena
Young Jung Ho-yeon (voice)
Park Ki-wook
Lee So-ri's Father (voice)
Kim Soon-mi
Doctor (voice)

73 Seconds
73 Seconds

The Karate Kid
The Karate Kid

Can You See Us?
Can You See Us?

Nemurubaka: Hypnic Jerks
Nemurubaka: Hypnic Jerks

North of Albany
North of Albany

Solo Leveling -ReAwakening-
Solo Leveling -ReAwakening-

Le Pion
Le Pion

Student Council Staff Members Movie
Student Council Staff Members Movie

NO CALL NO LIFE
NO CALL NO LIFE

Ben X
Ben X

Shining Modern History
Shining Modern History

Kino's Journey: Life Goes On
Kino's Journey: Life Goes On