The JoJo manga is mainly in black and white. Colored versions exist but are not the norm. Sometimes, colored illustrations are done for promotional purposes or by fans.
The Jojo manga is mainly presented in black and white. However, there might be some special editions or fan-colored versions out there, but those aren't the official ones.
Once upon a time in the world of Jojo, Jonathan Joestar was on a quest. He had to face the evil Dio. One night, as he was resting in an old, spooky mansion during his journey, he heard strange noises. But he wasn't afraid. He knew his Hamon powers would protect him. He got up, and with his brave heart, he explored the mansion. In the end, he found out it was just a stray cat that had made all the noise.
Well, the 'jojo's bizarre adventure novel' has a really complex plot. It spans generations of the Joestar family. There are different arcs, like the one where Dio Brando is a major villain. He has his own evil plans which often put the Joestars in great danger. And the characters keep evolving and facing new challenges in different locations around the world.