Hmmm. I did think Eba would die between November 23rd 1998 and April 9th 2001, but I didn't expect him to die on the exact same date as Hal... I didn't see any hints of Eba getting shot after he appeared when the lights got turned on, but one of the goon's gun was out of the panel, so maybe it was the one that fired. Since Eba located the bullet in the darkness (somehow he did this while also headshotting three goons, and he was smart enough to foresee the situation so far that he brought a paintball gun with fake blood in case Souichi lost - or perhaps it's a famous game that Fukurou likes to play often, and we saw that room full of guns where Eba was waiting for Souichi; but still, him bringing that gun with him is very coincidental), he then waited until Hal was about to lose and thus shoot himself, and (probably secretly?) shot Hal with the fake blood instead, somehow deceiving Fukurou and his goons, who was was probably the one that spread the rumors of Usogui sacrificing his comrade later on, since he thought he ran and had sent him instead to die. Fukurou must've ordered his goons to also get rid of the bodies or took them with him, since I doubt Eba in his current condition would be able to do that by himself. Then, after having Fukurou leave, and Souichi being safe but unconscious, he mustered up the last bit of strength he had to drag himself to his private room, where he keeps all his recordings, to record that day's events for implanting Souichi's memories, and then crawl up and die...
And then, the most unfortunate (or induced?) timing for a memory loss possible occurs. Hachina wakes up, having lost his memories again, and analyzes his surroundings to piece together the situation. Then, either via clues from the Prince Bee (I assume there must be some hidden clues for Hachina within the Prince Bee, since there were seemingly no obvious hidden instructions within it, or Baku would've found them, and yet the information inside was enough for Hal to know where to go. Which means that when Eba implanted Souichi's memory about coming to meet him, they must've put together some sort of code or interpretation of the book that allowed Hachina to deduce where to go without needing specific instructions. But at the end of the day Baku figured it out anyway, since we know that he buys the whole bookstore to hijack the book ordering process in Eba's stead in the future. Or perhaps he found out in another way) or simply by following Eba's blood trail, he finds his room, where he is met with Eba's dead body or his dying moments, after which he sits down on Eba's computer and gets all the memories he lost implanted through all of Eba's recordings.
The truly sad thing is... Hal was ready to abandon his life as Hachina and Souichi (and presumably also his father, since he would die if Baku were to win against him at StL) to become Hal and be with Baku... But instead, he loses the match, loses Eba, a very important person to him, and (probably) loses all his memories of Baku... I assume Baku must've suspected that Hal wouldn't come back even though he said it wouldn't be long, and even though Hal did intend to come back, at the end of the day he couldn't...
We'll need to see the next chapter to confirm some more of the details, but this is how I understood things so far.
Edit: Oh yeah, and it seems like Kaoru did get some details wrong, and Baku did lie a bit? I mean we didn't see Hal throw Baku's Pooyan run, and the night before he didn't eat plums with eel, but he ate clams, maybe he did that offscreen. Then, Kaoru had guessed that he had gotten drugged and Hal went in his stead, but in this situation Baku didn't even set up the meeting at all. It was all Hal after figuring out where Eba was and setting up the gamble there (to make sure to have someone to protect him) using Usogui's phone and/or voice.
Edit 2: Also, the probability that Eba lied to Souichi about some of the turn of events (perhaps to avoid him unnecessary pain) is quite high in my opinion, so we should take this with a grain of salt for now. Especially since Eba said he had seen where the bullet was in the dark, despite Fukurou having said that they made sure that it was impossible to see where the bullet is just by looking at it. I mean, he could've lied, but still.