Investigation Couple Guest cast, played by Yoon Sa Bong Episode 1x04: Episode 4 (May 15, 2018) Episode 1x05: Episode 5 (May 21, 2018) Episode 1x06: Episode 6 (May 21, 2018) Episode 1x07: Episode 7 (May 22, 2018) Episode 1x08: Episode 8 (May 22, 2018)
