The longest manga series could be considered 'Golgo 13'. It has persisted for a long time because of its unique storyline and dedicated fan base. Also, its consistent release schedule has contributed to its longevity.
The title of the longest manga series is often debated. 'Golgo 13' is considered long-running, as it has been published for decades and has a huge number of chapters. The longevity could be attributed to its wide appeal and diverse storylines.
'Death Note' has a really deep story. It's about a high - school student who finds a notebook that can kill anyone whose name is written in it. This manga explores morality, justice, and the corrupting influence of power in a very engaging and thought - provoking way.