Cordon

The school librarian, and Komaran's father. Neither of them are aware of this fact, as his memory was essentially wiped only a few years after her birth and she has been kept out of the loop as far as his appearance and whereabouts go.
He disappeared from his wife and daughter's life after making a deal with a nature spirit that overtook his body for several years after laying dormant for some time and essentially forced him into reclusion. After snapping out of his involuntary trance, he struck another deal and now is cohabiting his own body with the mushroom colony.
It has turned into a symbiotic relationship, and they see each other as invaluable partners.

The mushrooms engulf him during moments of stress; the more agitated they are, the more mushrooms grow.
This means they're nearly always sprouting when Louis is in the same room, as Cordon despises the man.
Louis finds this adorable.

While he is part of Mme Spiralshine's inner circle, he takes nearly no active part in the activities and turns against them when he finally learns of Ko's identity.

Cordon uses he/him for himself, and us/we when referring to the mushrooms as he considers them to be the same being. People use they/them when referring to the pair.

Good friends with Rosa.