The career of a mangaka is not an easy one. With the usual requirement to push out work every week, that typically means tight schedules for everyone involved with little downtime and long hours of grinding. Not only does a mangaka have to conceive and develop a timely story, they also have to draft the art for it as well. That's a lot of pressure every day to meet deadlines. As such, many niche mangas you see often are forced to close their stories early due to lack of interest, or failing to meet the publisher's strict requirements. Mangakas that have a long career in the industry are rare because of this, and Kentaro Miura is one of those rare exceptions. He loved his work, and to see him work for over thirty years is an extraordinary feat by itself. While his stories will never be complete now, his legacy lives on in the memories he's created in those thirty years.
Farewell Miura-san. Your watch has ended.