Board Thread:Manga Discussion/@comment-27082821-20171220152544/@comment-26389140-20171230170232

Or maybe All Might's "Heroic Form" is how OFA manifests trough his body. After all, the "Heroic Form" is practically Deku's "Full Cowl" created by Toshinori instead. What I'm saying is as Toshinori Yagi and Izuku Midoriya are different (especially in body), so that can mean OFA is manifested in various ways according the user. For Deku in this case, OFA is manifested like a new and shiny set veins/circulatory system made of energy fluiding though his body. And All Might manifested OFA granting himself such musculous form.