I loved the Guyver since I was in high-school and have just recently started reading the manga. It's been great because I've just read the first 25 volumes during the past 5 days.
I am also acutely aware that this has been going on since 1985 and that after 30 years, we only have 31 volumes and no ending in sight. It's gonna suck when I put down Volume 31
next week and start twiddling my thumbs whilst waiting for the next chapter but, hey what can you do right? The reason why the Guyver isn't popular is very simple. The Mangaka himself is lazy and can't be bothered anymore. Simple.
I was a big fan of Vinland Saga, a Norse manga which was winning awards all over the place and had a huge readership but you know what? The moment that
switched from weekly to monthly, its popularity took a nosedive. People became tired of waiting for the next chapter and before long that mangaka took breaks too.
Switching from weekly to monthly is probably a very welcome proposal as far as the mangaka are concerned as it means they can actually sleep and have a life but
unfortunately, it's also the kiss of death when it comes to popularity.
Takaya is obviously burned out and probably wishes he didn't have to do the series anymore but in all likelihood, it's probably his only source of income right now.
God knows how his editor puts up with his snail pace but I can only imagine that it's because the Guyver enjoyed a modicum of popularity in the 90s. This year is the 30th anniversary
so who knows, maybe he'll put his back into it and finish the story once for all. God knows it's taken him long enough!!