Friend was most likely the mysterious kid on ch 6 page 16 who talked about Lieutenant Collins. One of Kenji's friends that he can't remember because of the plot-induced CTE
They keep saying that Friend has enough followers to fill the Budokai, and a few chapters ago the narration said that Kenji's college friend would perform in front of a full Budokai 3 years later.
Urasawa the master strikes again with his masterful writing. The tension had me on the edge of my seat. Imagine reading this weekly when it first released