Matti, also known as Marty Tohn, serves in the Kingdom of Honnêamise's Royal Space Force. He becomes a close friend and confidant to protagonist Shirotsugh Lhadatt soon after Shirotsugh joins the program. Their bond forms early, with Matti appearing alongside Shirotsugh at a fellow Space Force member's funeral, both standing beside him in uniform.

Matti consistently shows loyalty and concern for Shirotsugh. He supports Shirotsugh during vulnerable moments, like offering comfort after the funeral. When Shirotsugh later goes AWOL amid disillusionment and crisis, Matti is visibly worried about his sudden disappearance and well-being.

Within the Space Force, Matti actively participates in training and operational activities alongside Shirotsugh and other cadets. He is present during group interactions and technical procedures for the first manned space mission launch, contributing camaraderie amidst the program's technical hurdles and political tensions. His documented role centers on his professional duties within the space program and his personal connection to Shirotsugh.