EDIT: Hey, the Famicom Detective Club remakes are also coming west! And with a May release, I really should speed up my Umineko playthrough...
Had to think of that art history professor I once had who had a real Japanese katana and actually walked around campus with the thing to show it off in the lecture room when the topic came up in class one day.
Inside the house, the four inspect the Demon Sword Shikabanemaru, which is kept safely in a glass case. They unsheathe the sword and are relieved to see that it's completely clean: not a sign of blood anywhere on the blade, nor does it look like it was wiped clean of blood moments ago. The sword is placed back in the case, and the four start to talk about Shikabanemaru's backstory, but suddenly, they notice blood leaking from the sheath. They quickly get the sword out of the glass case and unsheathe it, only to find the whole blade covered in blood! But how can the blade of Shikabanemaru's blade suddenly be covered in blood even though it had been put inside a glass case, unless it's really a Demon Blade? Even Homura doesn't know what to make of this grotesque mystery, until she later realizes what really happened in Nemoto Shou's Youtou Shikabanemaru ("The Demon Sword Shikabanemaru" 2020-2021), issue 19 of Kaiki Tantei Sharaku Homura, which can be read at Nemoto's Note site.
Kaiki Tantei Sharaku Homura ("Sharaku Homura: Detective of the Uncanny") is a doujin comic (self-published comic) by professional comic artist Nemoto Shou, which in recent years has also seen a digital three-volume release by a major publisher (reviews of the first, second and third volume here). The series is an excellent mystery comic focusing on impossible crimes and a great example of how to do fair-play visual mystery fiction in general, and they even have formal Challenges to the Reader! While Nemoto has released more issues beyond the material collected in the three collected volumes, there's been no talk yet about a fourth volume. I have however discussed a few of the non-collected issues already: Issue 16, Hagoromo no Kijo ("The Ogress With the Robe of Feathers"), was one of the best entries in the series about an impossible stabbing in a snow-covered field without any footprints of the murderer, while issue 18 Kourei Yashiki ("The House of Necromancy" 2020) presented an interesting impossible disappearance of a diamond. The latest issue too focuses on a non-murder mystery. Well, to be fair, a lot of people do die in the backstory of Shikabanemaru, but the main mystery of this tale is about how a clean, sheathed sword can suddenly become completely covered in blood.
Youtou Shikabanemaru is one of the shortest issues of the series and that is reflected in the mystery: for example, the list of characters is incredibly short, so most readers will probably have an idea who's most likely to be behind the magic of the bleeding blade, and from that point on, it's not that difficult to at least guess what they could've done to cause the blade to be covered in blood, even though it was clean when the sword was sheathed and put away in the glass case. The most obvious solution is luckily immediately discarded by Homura, as she shows that the easiest answer is definitely impossible, and this is properly supported by the artwork, which is always one of the things this series does best. But even so, the jump from there to the actual solution isn't that far, and it's basically a variation on the same idea. While I like the idea of the final hint Homura sees before she solves the case, I think the hinting could perhaps have been more focused on the specifics of what and how the culprit did it, rather than one step beyond: if for example the culprit did action A, for which they also needed to do action B, and for that they needed to do action C, the hinting in this story is focused on C, while it expects you to deduce A from that, which might be a bit too far, even most people will likely have a basic idea of what the solution will likely be.
Speaking of stories about demon swords that possess people and tempt them to killing other people, I don't think I have read that many mystery stories about this theme, even if it sounds like an appealing concept. In fact, the first thing I had to think of was not a mystery story, but the action series Dororo, where one of the earlier stories is also about a demonic sword possessing a swordsman into becoming a ruthless killer (the PS2 game released in the West as Blood Will Tell is great and also features this story by the way!). I recall one of the short stories of Kindaichi Shounen no Jikenbo also having a demon sword/knife or something like that and I'm probably forgetting a few I have read/seen, but even so, it's surprising I can't name more of them instantly.
I liked Youtou Shikabanemaru, the nineteenth issue of Kaiki Tantei Sharaku Homura, probably better as a horror story (the epilogue!) than as a mystery story, even if it's honestly not bad. It's a short story, so there's only so much you can expect of it considering the page count, but it has an original impossible mystery and interesting backstory, and while the solution to the mystery of the bleeding blade might be not as surprising as you might hope, it's still a well-written story that most of all tries to be fair at all times to the reader. But I'll have to be honest and say that after two short murder-less stories, I'm definitely looking forward to a longer murder mystery for the next issue!