: Ishibumi weaves together various pantheons, including Christian, Norse, and Japanese Youkai, into a cohesive universe where factions once at war now navigate complex political landscapes. Systemic Depth

His battle cry, "Boost!" becomes a metaphor for his growth. By Volume 12 ( The Crimson Wall of the Holy Sword’s Decision ), Issei performs an act of self-sacrifice so brutal and heroic that it cements him not as a lucky pervert, but as a true shonen protagonist on par with Naruto or Ichigo.