Kamen Rider J

The story begins with three Aliens in human form preparing for a ritual to feed the Fog Mother's "siblings". The Fog Mother last came to earth during the Prehistoric Age and is the cause of the extinction of the dinosaurs. Kenji (KR J) and his kid sister are in the mountains, Kenji is investigating all the deaths of animals and trees there. The Fog Mother sends the three aliens, "Prince Gorai", "Zoo", and "Agito" to kidnap Kenji's baby sister for the sacrifice. During the course, "Agito" punches through Kenji's stomach and plunges to his death. Or did he?