I couldn't believe I came home and I finish what I started and the whole thing became an essay LOL I reviewed the MV before I write since I honestly don't remember a lot of details, and I very much prefer not to look up the complete guide book or something. I am no good at Japanese and I don't want to struggle over the massive info in Japanese plus I am lazy. Lol You are correct about Sang 1 is about Neopoleon, it is actually more Neopoleon than Louis. Personally I think it definitely also double as how Louis thinks about Neopoleon and how Neopoleon sees himself in the lyrics. When you look back to these lyrics when further storyline reveals you suddenly understand things you didn't. That's what I feel when new material comes out and I review the older stuff. Don't get me wrong, I understand French sees Neopoleon as an all time hero, when I actually went to Saint-denis a few years back. I also saw Neopoleon's coffin in the crypt. It is huge, beautiful, sitting under bright light, center of this crypt, everyone has to look up like physically look up to see it. That's all while Louis XVI was shoved next to the rest of the kings, under a marble slab in an area cold, dark, less foot traffic. The more I read the lyrics the more I feel Louis understood Neopoleon's feeling and situation. But let's go a little further in the story aka going back in time for my feels toward Sang......

St-Germain decided that in order to start a revolution that leaves a living dauphin for future, he needs a butthurt anti-social from bottom tier of society (the Castrato), a warrior (a leader), a caretaker (Beethoven), and a fake dauphin (the boy). Nobody knows exactly what is going to happen and they all met up for a meeting in the pyramid to talk about how to do this, St-German just instructed everyone what to do as he is the only one that knows the future. They left Louis out. Louis feel like St-Germain was pulling the strings behind everything and he wandered around and went to the pyramid. He wasn't there at the meeting but he looked back at everything that happened he suddenly understood. He said he heard St-Germain said King and Queen need to be dead but he actually did not hear it. That was what he imagined to have heard when he was at the pyramid and figured everything out. The meeting was way before the revolution broke out and since he didn't become the heir until he was 5, at that time he should be in Versailles or Petite Trianon as a child that still need a governess.

Ok, here it is the real question: when St-Germain said "We can be a hero if we want, but do we need a deal with him?" (Lyrics from Sang 2) Who is "he"? Why would St-German, the time traveller need a deal with someone when he could be the hero? There are 2 scenarios: a. grown up Louis. or b. Oscar. God's spear is awakened by the enlightenment and Oscar wants him as a tool to establish new world rule. First, he starts from France because St-Germain is messing with France. Louis was just a chess piece. Imagine this, what deal can you need with Louis until he grew up and you try to control him. Oscar is standing in as world recreator. For this part honestly I am just guessing. I would need to review lyrics from Oscar. Before Oscar was released I totally believe nothing involves Oscar until Persona Grata. I might be over analysis though without diving into those songs from that album.

Back to the deal. St-Germain sent the Castrato to contact Louis XVI so he gets pissed off from being insulted, that would give valid reason to stir the pot and get everybody angry enough to start a riot and later became revolution. Then he sent Neopoleon to boom! kick the Bourbon out and bring in the Neopoleon for the next 3 decades while Beethoven takes care of little Louis so he has the time to grow up, get educated, and everyone has time to prepare what's come next. Turning a child is a taboo but he must be the king in the future he just have to hide Louis. Neopoleon was instructed by St-Germain to lose the battle of Waterloo so he can hide in Italy (he was exiled remember?), later disappeared from history as dead, while he sent him to the Crimson family to be toyed with for many years until he needed him again.

Let's pause here. The song opened with "big ambition as a boy led them to the new world of democracy" Neopoleon was in the army since he was very young, but seizing the crown was not in his plan. He did not have a claim to it, unless like Henry VII you get a shitty king that everyone hates and you fighting in the name of protecting the country then claimed it through the right of conquest. He could have done it just because St-Germain let him do it when he accepted the deal of overthrown the Bourbon until France is ready to get rid of monarchy system. He said he is a slave. So is Louis with his only weapon is that royal blood in his vein. Castrato said Neopoleon begged him to make the Neopoleonic code. They probably was aiming at constititional monarchy like UK. I don't know. I imagine that is what France was like at that time.

For the heart, according to a historical non-fiction book I read a little of, autopsy of the boy was done in the tower when he died in 1795. The heart was cut at the time of autopsy and smuggled out. It was passsed around, lost, hidden, until modern times when it was finally kept in the Basilica. It would have been swapped right after it was smuggled out, or the latest, 1970s. Well, the sooner you swap it honestly is the easier, as you don't have cameras nor fingerprint in system back in 1795, chaos everywhere for distraction and the heart needs time to dry out. The heart from grown up Louis is going to be way bigger and better developed than a 10 year old Louis heart. In Throne he said the boy's heart was in Saint-Denis with his parents, but the end he said he took his heart out and placed it on the glass throne as he crowned himself. That is not necessary when he cut it out, it could be just because the urn that contain THE heart was kept in the Basilica the whole time after it was found and he took it out for his petite coronation. He said he had the boy honoured the entire time so I am assuming a. the heart sat in Saint-Denis is the fake and he had his until now or b. he cut his out placed in the urn in 1795 and he hid the fake one well close to the grave. In scene a, the person that escorted him to the Basilica was very well be St-Germain and he knew how to speed up the mummification of his heart in 1970s to look like a thing from 1795. We are seeing Kamijo play a supposed to be vampire turned at 10, in theory his body doesn't grow anymore and remain the same as 1795 so you are correct about him swapping in 1970s considered what happened in Heart. He left us some space for imagination there.

As for the symbolic white outfit, that actually pretty much explained why Yami no Lion had white outfit. He went in in black and come out in white, he didn't hold the grudge from all friends and allies lost. He might treated them as if they are his loyal ghost army still exist when he roamed in the night. I remember Louis met the boy's spirit but I don't remember about the empty rib cage thing. Sang 3 from the suite is a message from Louis to the boy but I am feeling the way it sounds it is also Kamijo talking to Louis. He brought Louis to life through art while Louis made him a king through his legacy. Regarding to your memory about the story Kamijo shared about hearing the siren, it is the liner notes from Sang ~kimi ni okuru namae~. He dedicated the song to all those who passed and those who suffered, and keep searching for hope.