Ultraman Vol. 3 (manga)

The enigmatic Moroboshi takes Shinjiro, who is still having doubts about fighting as Ultraman, through a strange gate to a secret alien city. There he meets a new informant and cannot avoid getting mixed up in a feud beyond his control. Meanwhile on Earth, the police and the Science Patrol go deeper into a sinister investigation when a new victim of a mysterious serial killer turns up.