Letter from Secret is the fifth extended play (promoted fourth Korean EP) by South Korean girl group Secret.

"YooHoo", the album's lead single, marked the group's return to aegyo-inspired songs such as "Shy Boy" and "Starlight Moonlight".

"YooHoo" peaked at number 5 on the Gaon Singles Chart and has 978,757 downloads.

The EP has in total 1,063,071 DLs while it sold 8,532 copies.

These credits were adapted from the Letter from Secret liner notes.