Ultraman Mebius Side Story: Armored Darkness (2008)

Sometime after Alien Empera's destruction and Mebius' departure, Ryu was promoted into GUYS captain, leading a bunch of rookies whereas the older members had retired. After recently destroying a Saramandora, the group separated to fight three different monsters, Roberuga, Mukadender and Cherubim. Not long after destroying Mukadender, Ryu and Haruzaki's ship were sucked into a strange fireball that brought them into a pocket dimension, which was revealed to be none other than the late Empera's ship, Darkness Fear.

July 25, 2008, midnight

While both Cherubim and Roberuga were being dealt with, Mirai revealed to Haruzaki that Ryu survived the explosion. Ryu was briefly met by Ultraman King, later Hikari, who revealed that the giant armor's name was Armored Darkness, one of the Empera's vanguards.

Aug. 22, 2008, midnight