Gear Fourth is impossible without advanced Busoshoku Haki. Luffy coats his expanded muscles in a hardened shell. This serves two distinct purposes:
This paper examines the fourth transformative state (Gear Fourth) utilized by the pirate captain Monkey D. Luffy, derived from the Gomu Gomu no Mi (Paramecia-type Devil Fruit). Moving beyond the skeletal compression of Gear Second and the skeletal inflation of Gear Third, Gear Fourth represents a hybrid state: muscular inflation combined with Haki (Busoshoku: Ryuo). This analysis argues that Gear Fourth functions as a biological tension-fabric system, redistributing mass and reactive force to achieve aerial mobility, high-impact compression attacks, and defensive resilience. Furthermore, the paper explores the symbolic narrative function of the transformation’s aesthetic (the "Bounceman" and "Snakeman" variants) as representations of controlled chaos versus calculated predation. gear 4th
: A speed-focused form used against Charlotte Katakuri. It prioritizes rapid, unpredictable strikes that accelerate every time they bounce off the air. The Cost of Victory Gear Fourth is impossible without advanced Busoshoku Haki
The core mechanic of Gear Fourth bypasses normal human myology. In standard physiology, muscle contraction generates force via the sliding filament theory. In Gear Fourth, Luffy’s rubber muscles are hyper-inflated via air compression, then rigidified using Haki. Luffy, derived from the Gomu Gomu no Mi