Guide Mentor
Character Role Analysis
The Old Man
He's the most prominent adult mentioned other than the Eagle. Miles has a ton of respect for him, so the Old Man and what they study in his class become sort of a path for Miles's thoughts. Miles uses what they study in class as a way to think about Alaska, her death, and his own grief. Even though there's little personal interaction between Miles and the Old Man, we shouldn't underestimate the importance of his role in Miles's healing.
Takumi
Takumi's not nearly as important a guide as the Old Man, but he mentors Miles nonetheless. It's Takumi who tells Miles the truth about Alaska snitching on her roommate, it's Takumi who underlines the importance of not ratting, and it's Takumi who finally convinces Miles to stop being a total jerk and talk to Lara. So even though Takumi remains kind of a mystery, he at least helps Miles navigate his friendships at the Creek more than the Colonel and Alaska do.