Disclaimer: I haven't fully read wtf happened in IS 3 yet lol so I may mistake things here and there. Just brainrot.

Just like how Thorns knows he will use the potion to turn him into seaborn one day, he also knows, in the back of his mind, that the poison he created will definitely be used one day by the requester. Not to harm others, but to commit suicide.

About that 100 years later Miyabi with Temma Jr...
Temma-kun is in a loop like Miyabi, he's forever 20...until he becomes a full-fledged knight or something, right
I imagine he prolongs that as long as he can to keep Miyabi (and others) company, but eventually he has to graduate from being 20 years old, after all. That explains how his kid, 100 years later, might not be so old yet (or maybe the same logic applies to his kid - staying in a certain age until they reach a certain point).

[Long before Rhodes Island, in Victoria when Enciodas and Hana are college students.]

The two of them go out to have a dinner together. Hana suddenly uggests to have a drinking competition at a nearby bar because why not, and the loser has to pay for everything. Not wanting to lose, Enciodas of course accepts it.

There's a theory that Phantom came to Rhodes Island to assassinate someone there under someone's orders and was found out by Schwarz. Very plausible, but god knows who his target is.

In my AK universe or lore or whatever you call it, the target is Doctor.

It feels even more possible with Phantom's line: "I can end many lives for you, but I first need you to confirm that I am awake. Something is trying to influence me. It doesn’t want me to leave the stage. It wants my song to echo forever... and it wants me to kill you. Before I play the role of your assassin once more, I must discover the truth."

Dr. Hana is weird. She pays attention to celebrations and other people's birthdays, yet she doesn't really care about her own...

SilverAsh
After wrecking his brain, in their peaceful days in Victoria, Enciodas gave her an antique-looking box, saying that he'll give her something new to put in every year. Alas, he couldn't give anything to her for a few years when she went missing. Would be great if he gives her a ring someday. [Yes, this is totally from Persona 3 Portable, I just love this idea so much okay]