He completes the ritual. The smoke clears. The figure emerges.

Without specific references, one might imagine "Yondara" as a place, character, or event and "Haha-ga-Kita" as an arrival or occurrence. A succubus arriving in a scenario could imply:

Apparently, his mother had been reincarnated or transformed into a succubus in the afterlife (or another dimension), and when she sensed her son calling for a "woman," her maternal instincts—and her new demonic powers—dragged her right through the portal.