Sul Kyung-gu, Moon So-ri, Kim Yeo-jin, Suh Jung, Go Seo-hee, Kim In-kwon, Lee Dae-yeon, Gong Hyung-jin, Kim Kyung-ik, Park Se-beom, Jeong Woo-hyuk, Yoo Yeon-soo, Son Young-soon, Lee Jin-seong, Park Ji-yeong
In the spring of 1999, a group of old friends gather to celebrate their 20 year reunion. Among the group is Yeong-ho, a cold, unhappy man, whose demeanor puts a damper on the festivities. The seriousness of Yeong-ho's depression becomes apparent when he climbs a railroad bridge and looks like he might jump. At this crucial moment, memories of seven crucial episodes from Yeong-ho's past flood his mind.
Very well done and quite creative. Rather than create any spoilers, I'll just say that it's all revealed backwards.