Masamori's Plot - S1.E14

Yoshimori is really annoyed with Masamori being back especially when he thinks about how Tokine paid more attention to Masamori even in their childhood than to him. At night, Yoshimori and Tokine go to Karasumori and are confused when they can't find the ayakashi but then all of a sudden a forest grows and envelopes the school grounds. Madarao mentally notes that plant-type ayakashi cannot move and so someone must have planted it there. Masamori watches from afar and it is revealed that he was the one who planted it. Using the backdraft phenomenon suggested by Yoshimori, the two are able to destroy the ayakashi, although they had a huge mess to clean up afterward.