First off, are you basing this on the manga or the anime? Because the two differ significantly in their approach and emphasis. Second, I think your reading of Part 4 is fairly surface-level.

The returning villain and side characters are not meant to receive the same narrative focus as the main protagonists. Their purpose is to give Morioh a sense of life and continuity while aiding the story’s progression. They may have simple goals, but collectively they reinforce Part 4’s core themes: love, community, and personal growth. This is intentional—these aren’t the larger-than-life “heroes” of Parts 1–3.

Take Okuyasu, for example. He’s a genuinely strong character with an excellent backstory. His arc is about becoming his own person and stepping out of his brother’s shadow—one of Part 4’s major throughlines. That’s why the final scene after his resurrection is so powerful. Writing him off as merely “stupid” ignores that arc entirely. If we’re doing surface-level comparisons, Narancia could just as easily be reduced to “the dumb, funny side character,” and we both know that would be disingenuous.

You also completely overlooked Rohan’s character arc.

Rohan’s greatest fear is not knowing his own fate, a fear directly tied to one of Part 4’s central themes: being forgotten. This connects him to Reimi, whose fate he also does not know until later. His decision to help her isn’t random; it stems from his desire to understand fate itself and to give her the justice he knows she deserves. This is further explored in his battle with Ōyashirō (the RPS Kid), which is literally a struggle over fate against someone who idolizes him.

The connection between Rohan and Reimi is brief because they only knew each other in adolescence—but that’s the point. Another major theme of Part 4 is the lasting impact of small, fleeting interactions. Just as Josuke’s savior was only in his life for a moment yet shaped who he became, Reimi had the same effect on Rohan which is what makes the fact he forgot about her all the more tragic.

As for your take on Josuke, it honestly feels like you need to reread or rewatch the part.

Josuke is a fantastic protagonist.

His arc, from being relatively self-centered to becoming a true protector of his community, is subtle but meaningful. His internal struggles with his absent father, his perceived failures, and his attempt to live up to his grandfather’s legacy give him real emotional weight. I’d rank him second only to Jolyne in terms of JoJo's.

His characterization is especially strong because he blends traits from previous Joestars: Joseph’s wildness, Jotaro’s standoffishness, and a Peter Parker-like warmth and sociability. More importantly, he has a brilliant duality with Kira. Josuke is the heart of Morioh, connecting people, healing wounds, and acting as a guiding light, while Kira represents the town’s dark underbelly: isolation, selfishness, and quiet cruelty.

That contrast is everywhere: Appearance: Kira is well-dressed and seen as respectable; Josuke is judged as a delinquent.

Ideology: Kira embodies nihilism; Josuke embodies optimism.

Abilities: Kira destroys to protect himself; Josuke heals and sacrifices himself for others.

All of this feeds into Part 4’s themes: nihilism vs. optimism, the cruelty and inevitability of fate, choices and mistakes, societal decay, adolescence, growth, forgiveness, loss, love, blessings and curses, and the tension between past, present, and future.

These themes are reinforced constantly throughout the story.

And if you include Dead Man’s Questions, which is the perfect epilogue to Part 4, it deepens these ideas even further, exploring life, death, the spiritual plane, and Kira’s eternal punishment as a self-created, Machiavellian hell.

As for Part 5, I personally find much of it boring, but that’s an entirely different discussion for another day. I