Often, it's a matter of cost and effort. Coloring each panel takes a lot of resources. Also, some artists prefer the artistic expression in black and white.
One reason could be that coloring manga pages takes a lot of time and effort. It's much more work-intensive than black and white.
One reason could be that coloring manga pages takes a lot of time and effort, making it less feasible for regular production.
One reason could be that black and white allows for more emphasis on linework and shading, creating a unique artistic style.
Another factor could be that in some cases, leaving manga uncolored allows for more imagination on the part of the reader. They can envision the colors in their own way. Plus, it's a traditional approach that has been followed for a long time in the manga industry.
One reason could be that coloring manga is very time-consuming and costly. It requires a lot of effort and resources from the artists.
Cost is a big factor. Coloring manga pages takes a lot of time and resources, making it expensive.
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 Bleach manga is not colored. It's common for manga to be in black and white to focus on the line art and storytelling. Color versions might exist in certain promotions or adaptations, but the core manga is monochrome.
Generally, manga are black and white. This is mainly due to cost and production time constraints. However, some popular series might have colored pages for special chapters or volumes.
You can search for colored manga on specialized manga websites or platforms. Some artists or groups might upload colored versions of popular manga there.