Trio vocal group Monday Kiz will be spending their Christmas holidays with their fans through a special 2-day concert, titled "Love Letter",�running from December 24th - 26th. During the concert, the boys will be revealing two songs from their five-track mini-album, scheduled for release sometime in January. This will mark their return after seven months, when they released their fourth album "ru:t;" back in May. Additionally, it's been reported that the "Love Letter" concert tickets sold out immediately after they were available for sale, proving their popularity as one of the best vocal groups in Korea. For those who aren't familiar with their work, check out "Don't Go," Monday Kiz's title track from their "ru:t;" album. Source + Photo: Newsen