If you're a manga reader, you know it can be difficult to follow complex stories with monthly issues. For example, the latter half of Attack on Titan must be read in one run to fully appreciate its depth. I think this is precisely why it lost some of its popularity toward the end of the story-it was too complicated, and casual readers couldn't easily follow the storyline.
The same is true for "Tengoku Daimakyo." I've appreciated the mangaka's other works, such as And Yet the Town Moves and other short stories (all interesting and mixtures of humor and mystery). However, I stopped reading Tengoku Daimakyo around 30 chapters in, simply because it took too long for the next chapters to become available.
The show is a godsend. It has incredible illustration, ambiance, and music. It captures the strong chemistry of the two leads, and the story never shies away from confronting the more controversial philosophical questions (e.g., who are you if you are in someone else's body?).
Watching the series within three days allowed me to see connections that I completely failed to see when I first read the manga. Once you understand how the two storylines intertwine, all those minor visual cues carry much more significant emotional weight (e.g., the view of the sky in episodes 8 and 12).
This show is a mental puzzle with answers lying right in front of you (which reminds me a bit of "The Prestige"), and the reveals are done in such elegant ways that you have to devote your full attention to feel its impact.
You can clearly see influences from Satoshi Kon, Akira, and even some of Doraemon.
After finishing season 1, I re-read the manga and found the answer to many outstanding questions, but there are still significant unanswered questions that remain. I am eager to see Season 2, as I believe if the manga concludes in a satisfactory manner, this series will be known as a masterpiece in the history of animation.