[vin13ish]

Who is the deuteragonist of Kamen Rider Ghost?

I am planning to make a thread about the deuteragonist of Kamen Rider and while I know which one is the deuteragonist from each Rider show but i having a hard time to figure out which character from Ghost is the deuteragonist to Takeru's protagonist.

Deuteragonist is the second most important character after the Protagonist and they are the one who is involved with the story the most.

But Ghost is rather tricky for me to figure out of who is the deuteragonist.

Who do you think is the deuteragonist of Ghost?