Daily Yo-kai Watch Factsさんのイラストまとめ

In the game Yo-kai Gakuen Y Wai Wai Gakuen Seikatsu, Chiaki Hebiyama is confirmed to be a reincarnation of a Yo-kai. However he is the only one whose Yo-kai from their previous life is unknown and he is speculated to either be the reincarnation of Venoct or City Licker.

Gabby's Japanese name could be a reference to Princess Peach from the Super Mario series, being that her name is "Speech-hime" and Peach's Japanese name being "Peach-hime".

After Shien's death in M05, Shien was split into a good half and a bad half. The good half became Lord Enma. Yo-kai Watch 4 implies that the bad half is Lucas. Shien's ++ Blasters mission is even called "Hi no kage ni nemurishi maou". Lucas' name in Japanese is "Hikage Mao".