Sammy, the division within SEGA-Sammy that does pachinko and pachislot machines, which is why no one is really surprised that they announced a Valkyria Chronicles pachinko machine. SEGA’s console division is reviving the Valkyria Chronicles brand with Valkyria Chronicles 4 in 2018, seems that Sammy finds the IP enticing enough for a pachislot machine. Sammy previously did a Bayonetta pachislot machine in 2015.
As far as when its coming, we don’t know anything outside of ‘coming soon’. I guess no one here will get to or want to play a Valkyria Chronicles pachislot game. According to this tweet by Sammy, they will have a preview tomorrow.