This game... really is an odd one. I'm almost sad it's an H-game, because underneath that label, there's actually a pretty great RPG to be found. Yumenamakon has put a lot of effort into it. There's standard xp-based levelling, key items that can be found in the world to unlock powerups of your choosing and finally a great deal of equipment to be found and also crafted. Even a food system for temporary buffs exists. Very in-depth, all in all. The story is quite intriguing as well, at least from what I could tell with just machine translation.
Unfortunately, as Mikufanboy correctly pointed out, there's more game than H-game to be found here, which is not what the majority of people here will be looking for.
As for the H-content, I actually enjoyed most of it. Which is highly unusual for me, as I'm only interested in femdom most times. This game has "consensual" as its main theme. At most there are some scenes where a girl get frisky with the MC and in some others the MC gets a bit rough with them. For anyone who wants to know how to unlock the scenes, there's basically six types of them.
Power transfer: In various spots around the world, some in hidden spots and some at the end of dungeons, you can find items called "pure material". Using this material, you can unlock new powers for the MC and the girls in a library-like room in the castle. Every so often, you'll unlock a special power that can be passed to the girls via H-scene in a room on the second floor of the castle. There's four of these for each girl (except for the maid), I believe.
Room H-scenes: The condition for these ones should be either having completed all of the power transfer scenes or being close to the end of the main story. You'll find the three girls in their rooms on the second floor of the castle (to the left). Just talk to them.
Sugar (the mage girl) actually has a second one. The condition is a bit obscure. When you talk to the maid in the dining room of the castle, she will at some point mention wanting to make the ultimate dessert, using "Eden Strawberry". Couldn't find the strawberry for the life of me despite looking where I think it should be, but cheating it in works just find. Give her the strawberry, enjoy the neat little scene of girls eating dessert, and afterwards you'll find Sugar in her room.
Maid scenes: The maid isn't an active companion, so she gets no powerups. You'll generally find her hanging around in the courtyard of the castle. Whenever she's found on the ground floor instead, there's a H-scene waiting for you. I am entirely clueless as to what the trigger for that is though. After more investigation, there's four of these scenes for her, and I couldn't get the last one to trigger no matter what. It might be a bug for all I know. That said, you can use the tool I linked at the bottom of the post to manually set the switch required for this scene to show in the gallery to 'true'.
Night crawling: Again, I have no idea about the trigger for these, but depending on who you have in your party, selecting the "Camp" option at a checkpoint (the one in your room works too) can result in a scene where one of the girls comes to visit you at night. I do believe you need to have progressed a good bit into the power transfer scenes for this to happen. This happens only for the companions, not the maid.
"Continuation" scenes: These ones are simple. Whenever you've had any of the above scenes (mostly power transfer ones, I believe), take a nap in your room. This will often trigger a short continuation scene using the same CGs as the "trigger scene". Each girl has three of these, with only the maid having two.
"Threesome" scene: There's a single one of these, with Semet and Ann (catgirl and knight). I don't know what the trigger is, but I can hazard a guess. In the Isra Desert, there's one oasis with a lake you can enter. Do so with the two girls in your party and interact with the sparkling spot to trigger a little non-H bathing scene. If my guess is right, the threesome scene can trigger afterwards.
I hope this will help anyone actually wanting to play the game. I also highly recommend this tool for easy MTL if you do:
https://ulmf.org/threads/tool-rpg-maker-mv-mz-vxace-vx-xp-wolf-rpg-cheat-auto-translate-tool.14436/
Edit: I finished the game. Definitely a fantastic RPG. Also, according to the little info board in the gallery, I should have all the CG's unlocked. Updated the sections above with relevant information.