Oh man that's not one, not two, but 3 severe health problems, I am just glad that he managed to go into hiatus before things got worse, he really should focus on recovery, the manga will probably take a good decade to re initiate, but I want to believe it can be done
I don‘t get why so many mangaka seem to be so averse to let someone else do the artwork. Togashi and Oda too. Is it a pride thing?
Imo the manga industry should encourage much more duos. Better work-life-balance for the author and artist and (on average) better manga quality for us readers. Win-win.
It is part industry standard, part culture, and part pride thing
Naoki Urasawa (author of Monster, 20th century Boys, etc.) has a series of documentaries called Manben, in which he interviews and follows different mangaka as they do their work for a day
Two episodes of note were the one with Takao Saito (RIP) the author of Golgo 13, who despite being on his 80s and with plenty of body aches refused to hand work to any assistants, to the point that Urasawa himself was impressed by his tenacity
The other episode was on Chiba Tetsuya the author of Ashita no Joe (yes believe it or not he is still alive and drawing), who also bears the full burden of the process, only handing the finishing details to his assistants, one of them being his own wife
Chiba is a special case because he has been making manga recounting his life and process and revealing the secret of how he managed to outlive everyone (his secret is to take things easy and slow, with breaks and exercise, which is also working for Go Nagai), and will probably reach 100 and keep working, however one thing doesn't changes, despite his more laid back attitude and relaxing work flow, at the end of the day, he still has to be the one that writes and draws the whole thing, having help being a last resource
It is a common aspect in the field, because mangaka (or gekiga in the case of the late Takao Saito) see themselves as craftsmen whose craft can only by done by their own hands, this is also why it was so hard for them to switch to digital tools, anything that seems like it could replace the authorship factor, being new technology or more people, is seen with aversion
The concept of a mangaka as an author is tied directly to the ability to put ideas into paper, it is not enough to have good imagination, being in a directorial or producer like position is pretty rare, the mangaka has to both write and draw the final product, despite the fact that just making the script, writing the plot, and coming with the setting and characters is already a monumental process
This problem also extends to core things like the quality of available media, not everyone who is good at drawing is good at writing, but since a mangaka has to do both we end with a saturation of works that look nice but are either boring, generic, or just plain shoddy, and while just pairing the artist with a good writer could fix things this is rarely encouraged, because manga also has a reputation still to this very day of being a type of media meant to be easily consumed, to be read while you are on a train commuting from work, or at lunchtime, etc
Thus there's more of an emphasis on the ability of being able to draw, than the ability of being able to write, and being able to direct is an afterthought really, which leads to the problem we now have
Boy how would I love to get a new manga by Umezu Kazuo, but he is so old now that he probably would end up hospitalized if he started drawing again, in fact I believe there was some news about him coming out of retirement back in 2021, but I haven't heard anything else ever since, this could have been easily solved if he had someone else drawing it, but that's just not how they roll