The title of the series is JoJo's Bizarre Adventure, but first and foremost, I actually wanted to draw Dio. Good and evil, white and black—Jonathan and Dio function as symbols and are foils of one another. The series had the potential to go on, so in my mind, I wanted to create a "first Joestar" that could function as a symbol of purity and dignity rather than a unique, fresh character—that's why it was hard to come up with him.
There are limitations on how I could write the character because he was a "symbol of justice," so he may be a little on the boring side. I solidified his character as I went. Jonathan is passive, reacting to Dio's various attacks, and this leads to him discovering his way of life. Perhaps this is linked to me as an author, growing along with my character as I drew him. Just as Jonathan was unsure as to how to live his life, I was unsure where to take the character. Maybe I grew as an author a little with Jonathan as he trudged on through his hardships.
I also wanted Jonathan to exude an aura of strength like in Karate Baka Ichidai after doing martial arts training alone in the mountains. As a child, I loved karate manga—you would see all kinds of supernatural strength, like punching electrical poles and having the birds on the wires drop down or someone trying to stab another person with a knife, only to have the knife bend. In actuality, martial arts does have a certain mystique to it, such as strengthening punches with breathing techniques. I wanted to include supernatural things like that in JoJo, and I believe that the Ripple is inspired by my love of karate manga.