The shifting, generation-crossing story setup of JoJo's Bizarre Adventure pretty well lends itself to spin-offs and crossovers with itself. Part 4, Diamond is Unbreakable had a better part of its plot driven by characters returning from Stardust Crusaders (and earlier!) to ostensibly contend with the leftover legacy of the defeated Dio Brando. So naturally there's some curiosity about what became of the wider cast in the decade and change between the third and fourth parts. And therein lies the driving force of the new spin-off manga Shining Diamond's Demonic Heartbreak. Coming to us not from Hirohiko Araki himself, but Kohei Kadono (of Boogiepop fame) and artist Tasuku Karasuma, this manga strives to answer the burning question I'm sure some fans were asking: Whatever happened to Hol Horse?

I can be a little facetious there, but Hol Horse isn't not a relevant character for a side project like this. As far as antagonists go, he's memorable and entertaining. If he wasn't extremely deep, he had a few facets to him that could be explored. That's at least more going on than so many of the other one-off villains from JoJo's, which Demonic Heartbreak is happy to remind you of early on. Kenny G was a character in this at one point, and they had to call him Billie Jean in the localization. Some of the other drop-in Dio deferrals are slightly more memorable. It's neat to see Mariah and her magnet powers again, and Boingo favors prominently into this plot mechanically, at least, if not in terms of his own actual page time.

Hol Horse linking up with Josuke relatively early doesn't spread the story into an ensemble piece. Josuke is a curiosity from Hol Horse's point of view at this stage. The fact that this plot is set before the events of Diamond is Unbreakable means there are limitations to what can be done with Josuke's character before his arc properly starts in his own story. Maybe this plot will retroactively seed some elements of Josuke's character that propelled him in his story, and there are some mechanical elements at play here, such as this being the point where he learned about Stands after already having his own. Despite being set in the time and place of Part 4, Demonic Heartbreak's focus is firmly on following up on elements of Part 3.

This tracks with the centering of Hol Horse and the use of other former Dio henchmen, anchored by the question of what all these people even did after the big bad glampire finally died. And it's already interesting to see Kadono's writing working to reframe these former villains in a much more sympathetic light. There's a decided bent to the portrayal of characters like Hol Horse and Mariah that they were primarily swayed by Dio's dramatic charisma into choosing the wrong side, and now find themselves living listlessly with regret about what they did and can do moving forward. For Hol Horse, along with Boingo, that means following up on one of Dio's many other loose threads, helping out the mother of the guy who trained Pet Shop by finding a similarly skilled parrot. Hol Horse is ostensibly doing this out of his code of chivalry, but as the story goes on, it becomes apparent this is as much about facing down his Dio-shaped past demons as it is retrieving a lost bird.

The eye towards the past is not subtle in the themes and presentation of Demonic Heartbreak. The Stand power of the parrot, Pet Sounds, that Hol Horse faces is the ability to directly repeat and replay past parts of the JoJo's story involving Dio. This includes hits like forcing that senator to mow down all those people by driving on the sidewalk, as well as making Hol Horse watch a rerun of his failure to betray and kill Dio. It's franchise fanservice, to be sure, but it also works decently (if also bluntly) with the theming of these characters trapped by their past actions, unable to move on.

That's a solid start for the Hol Horse half of the story, with Demonic Heartbreak then revealing that its focus on the legacy of Dio's servants goes back a bit further. Remember that Noriaki Kakyoin started way back as a flesh-bud-controlled flunky for Dio. It turns out he has a cousin named Ryoko (who goes by the very endearing "Ryon-Ryon") who was there to see him get picked up by the bad Brando and has spent all this time wondering what happened to him. The idea of Dio's thrall having family of their own dealing with their fallout is one that's been touched on before, not least of all with the Nijimura siblings in Diamond is Unbreakable itself. In Ryon-Ryon's case, it seems her following up on Kakyoin is meant to tie into the broader themes of the sympathetic humanities of those who followed Dio, alongside its ideas of perspective.

However, Ryoko's utilization in the plot so far is a mixed bag where the writing oddly chooses to use some of the weakest qualities of JoJo's. Specifically, Boingo's placement in the plot is primarily so Ryoko can get her hands on his Stand, the book Thoth, and follow its predictions to learn the truth about her cousin. This brings back the old fundamental problem of Thoth as a plot device, which is the implacability of its predictions. There isn't much those interacting with it can do save for reacting to its running commentary on things destined to happen anyway. This story may be set up to do something more interesting with this infamous book's abilities, implying towards the end that its influence might be turning Ryoko into the actual villain of this piece. As of now, it's only provided some funky drawings alongside Ryon-Ryon stumbling into situations she was already going to regardless. The actual plot is interesting, but as with all things involving Thoth, it makes you question the point of even having it in this story.

I can generously leave that in "Let's see where that goes" territory for now. The main story with Hol Horse and Josuke is solidly compelling so far, providing its unique perspective on parts of JoJo's that had previously so pointedly been left in the past. Karasuma's art complements Kadono's writing and seems up to sustain this story. Karasuma has a handle on having these characters do their distinctive JoJo poses even when not being drawn by Araki, with a take making everyone very "pretty" in a way distinct from the man himself. There's plenty of big-panel, moment-to-moment dynamism in the action scenes, keeping things moving in a way distinctly different from how Araki has done it. Comparison to JoJo's original author is inevitable and encouraged in a case like this, so it's a compliment that Karasuma can stand up solidly enough.

Is that enough to carry Demonic Heartbreak at this stage? Even as a spin-off, it doesn't feel super-consequential as far as development goes. It's a treat for established fans, bringing back appreciated characters from the older ensembles and exploring them with more sympathy. Whether you can buy that for a character like Hol Horse or follow up on Kakyoin after he's been dead and buried for so long is going to be up to you. This first volume doesn't overstay its welcome, so it's probably worth a quick check-out. It caters to me a bit as a certified Part 4 enjoyer and has piqued my curiosity at least.