Ok, points to raise for a plan...
- Because the survival and training of the future Infernals is a key part of the group's objectives, obviously the survival of the current Infernals is of paramount importance to make that possible. Survival is more likely if everyone here is working together, rather than scattered. Kaguya, Milly, and yourself are all currently in Japan and should be able to work together readily. Rakshata has already shown interest in coming to Japan, and we are more than willing to have Kallen be the test pilot for the Guren Mk-II. That leaves the matter of Akito and Leila.
-- You believe it to be essential for Akito to be near your team in order to fight any kill-teams sent after your group. Akito is a Slayer, and therefore likely to be a warrior of great power. While you can easily make yourself an elite Knightmare pilot thanks to your Caste's favored abilities, you are limited in the time and effort you can spend making yourself personally capable in other areas of combat given your other responsibilities. You suspect the others are in a similar situation, being focused on political efforts in the case of Milly and Kaguya or scientific pursuits in the case of Rakshata. To balance this out the four of you need Akito close by.
-- Now, unless Akito and Leila are willing to abandon their positions in the EU military and their W-0 unit - something you suspect at least Leila will be strongly against - their superiors would need to be convinced to send their unit to Japan to work your own forces towards the goal of liberating Japan from Britannia. Akito is somewhat hard to read, but his general attitude and rapport with Leila Malcal suggest he's likely personally loyal to her rather than the EU's military, and as such it is Miss Malcal you will need to convince.
--- Given her own treatment of Akito she does not seem to discriminate against the Japanese. As such you doubt she'd approve of her unit being sent on suicide missions. Convincing her that working with you is more likely to ensure their survival, as you would not treat her people as disposable. Further, given her unit is using prototypes you would think she's working closely with scientists and engineers. You are certain that Rakshata would be eager to see their work, and could likely help them improve upon it, which would further increase the chance of her people surviving any conflict.
--- If she seems particularly sympathetic to the status of the Japanese refugees in the EU, which you suspect is not good given what you've learned, point out that with Japan being liberated they could return to their home nation. There they would not be unjustly discriminated against, and could lead happier lives.
- As an extension of that, you need to speak about how Japan fits into your plans as the ideal beachhead for the Reclamation as well as a vital linchpin to any effort for defeating Britannia.
-- Japan contains 70% of the world's known Sakuradite reserves. This makes Japan a strategic location with few equals in the world.
--- By freeing Japan from Britannia's control it severely weakens their ability to wage war abroad. From Knightmares to common guns, the Britannian war machine runs on Sakuradite. Similarly, that advantage could become that of the Reclamation if Japan comes under its control.
---- This is also a good negotiation point with the EU for sending the W-0 unit to Japan. The geographic location of Japan makes it impossible for the EU to gain control it, as they'd have to go through either Britannia or the Chinese Federation, neither of which is possible. An independent Japan is therefore better for them, especially if they have friendly relations. Britannia would be weakened, and their other rival wouldn't gain an advantage either, but by helping the revolution they could gain an advantage from increased Sakuradite sent to them. Also, just for completeness of the argument to present to the EU, if your revolution were to fail (something you assure Lord Ligier will not happen) the EU already views W-0 as disposable and could simply claim the group went rogue, but still get the combat data for the Alexanders. Participation is a win-win situation for them.
-- With Japan freed, showing that an Area can liberate itself, rebellion will increase in other places conquered by Britannia, further weakening it.
-- Japan is an ideal location to lay the foundation for achieving the objective Oramus has given you - creating an empire greater and more unique than Britannia. While greatness and uniqueness are somewhat subjective in nature, it should very much be possible to eventually meet both criteria. This is also a good platform that may be helpful for meeting the orders of the other Infernals here. For example, Milly has been ordered to have people renounce the rigid laws of Area 11, and so you could make your empire more unique by encouraging a more free thinking, fun loving culture among the citizens of your empire. You are certain you can work in other goals as well.
--- Very importantly, addressing this final point to Lord Ligier specifically, is that any empire you build must encourage it's people to worship the Yozis. Japan is, again, ideal for this, as there are many disenfranchised people and cults have already begun being built. The cursed and corrupt gods have done nothing to help them, so the Yozis and their champions are obvious alternatives. With Japan under your rule and worshiping the the Yozis, your empire will become a subordinate kingdom to Hell, one that recognizes the world's True Masters and serves their ends.
I'll still need to work on a stunt and figure out how best to use our Charms here (likely just Excellencies to increase the dice pool), likely for convincing Leila, but if anyone has any thoughts on anything to change, add, or remove please let me know.