A theory about Akira being a parallel of SMT1 Hero / AU SMT1 Hero and how it relates to Nanashi's journey in SMTIV: Apocalypse.
SMTI
Is the Shin Megami Tensei Series Anime? A Friend of mine takes a shot at answering that question
Be warned it spoils SMT1, SMT2, SMT3 Nocturne, SMT4, and a bunch of animes made by Go Nagai and Megazone 23.